Add PostalAddress metabox to events. Can be used in events schema

events-metabox-for-address.php

<?php
/*
Plugin Name: WPMUDEV - Events PostalAddress
Plugin URI: https://premium.wpmudev.org/
Description: Add PostalAddress metabox to events
Author: Panos Lyrakis @ WPMUDEV
Author URI: https://premium.wpmudev.org/
License: GPLv2 or later
*/

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

if ( ! class_exists( 'WPMUDEV_Events_PostalAddress' ) ) {
    
	class WPMUDEV_Events_PostalAddress {
        
		private static $_instance = null;

		public static function get_instance() {
			if( is_null( self::$_instance ) ){
				self::$_instance = new WPMUDEV_Events_PostalAddress();
			}
			return self::$_instance;
		}
        
		public function __construct() {
            
            add_action( 'add_meta_boxes_incsub_event', array( $this, 'add_address_meta_box' ), 10 );
            add_action( 'save_post', array( $this, 'save_address_meta' ), 10, 2 );
            
        }
        
        public function add_address_meta_box( $post ){
            
            add_meta_box(
                'wpmudev-PostalAddress_metabox',
                __( 'Event Address' ),
                array( $this, 'event_address_metabox' ),
                $post->post_type,
                'side',
                'core'
            );
            
        }
        
        public function event_address_metabox( $post ){
            
            $address_data = get_post_meta( $post->ID, 'incsub_event_address', true );
            $street_address = isset( $address_data[ 'streetAddress' ] ) ? $address_data[ 'streetAddress' ] : '';
            $address_locality = isset( $address_data[ 'addressLocality' ] ) ? $address_data[ 'addressLocality' ] : '';
            $address_region = isset( $address_data[ 'addressRegion' ] ) ? $address_data[ 'addressRegion' ] : '';
            $postal_code = isset( $address_data[ 'postalCode' ] ) ? $address_data[ 'postalCode' ] : '';
            
            $content  = '';

            $content .= '<div class="eab_meta_box">';
            
                $content .= '<input type="hidden" name="incsub_event_address_meta" value="1" />';
                $content .= '<div class="misc-eab-section" >';
                    $content .= '<div class="eab_meta_column_box top"><label for="incsub_event_address" id="incsub_event_address_label">'.__('Event address').'</label></div>';

                    $content .= '<div class="misc-eab-section eab-address-section">';

                        $content .= '<div class="misc-eab-subsection eab-address-subsection">';
                        $content .= '<label>' . __('Street address') . '</label> ';
                        $content .= '<input type="text" name="incsub_event_address[streetAddress]" value="' . $street_address . '" />';
                        $content .= '</div>';

                        $content .= '<div class="misc-eab-subsection eab-address-subsection"> ';
                        $content .= '<label>' . __('Locality') . '</label>';
                        $content .= '<input type="text" name="incsub_event_address[addressLocality]" value="' . $address_locality . '" />';
                        $content .= '</div>';

                        $content .= '<div class="misc-eab-subsection eab-address-subsection"> ';
                        $content .= '<label>' . __('Region') . '</label>';
                        $content .= '<input type="text" name="incsub_event_address[addressRegion]" value="' . $address_region . '" />';
                        $content .= '</div>';

                        $content .= '<div class="misc-eab-subsection eab-address-subsection"> ';
                        $content .= '<label>' . __('ZIP Code') . '</label>';
                        $content .= '<input type="text" name="incsub_event_address[postalCode]" value="' . $postal_code . '" />';
                        $content .= '</div>';

                    $content .= '</div>';

                $content .= '</div>';
            $content .= '</div>';
            
            echo $content;
            
        }
                       
        public function save_address_meta( $post_id, $post ){
            
            if( !isset( $_POST['incsub_event_address'] ) || !current_user_can( 'edit_post', $post_id ) || $post->post_type != 'incsub_event' ){
                return;
            }
                       
            if ( defined('DOING_AUTOSAVE') && DOING_AUTOSAVE ){
                return $post_id;         
            }            
            
            update_post_meta($post_id, 'incsub_event_address', array_map('strip_tags', $_POST['incsub_event_address']) );
                    
        }
        
    }
    
    add_action( 'plugins_loaded', function(){
		$GLOBALS['WPMUDEV_Events_PostalAddress'] = WPMUDEV_Events_PostalAddress::get_instance();
	}, 10 );
    
}

Unfortunately currently there is no filter to edit the schema of the event. In order to add the PostalAddress markup in the event you should edit file:
events-and-bookings/lib/class_eab_template.php

and change method get_event_details() to

`public static function get_event_details ($post) {
$content = '';
$data = Eab_Options::get_instance();
$event = ($post instanceof Eab_EventModel) ? $post : new Eab_EventModel($post);

	$content .= '<div class="wpmudevevents-date">' . self::get_event_dates($event) . '</div>';
    
	if ($event->has_venue()) {
		$venue = $event->get_venue_location(Eab_EventModel::VENUE_AS_ADDRESS);
		$address = '';
        
		$content .= "<div class='wpmudevevents-location' itemprop='location' itemscope itemtype='http://schema.org/Place'>
                        <span itemprop='name'>{$venue}</span>";
        
        
        $address_data = get_post_meta( $event->_event_id, 'incsub_event_address', true );

        if( isset( $address_data['streetAddress'] ) && $address_data['streetAddress'] != '' ){
            $address .= "<span itemprop='streetAddress'>{$address_data['streetAddress']}</span><br />";
        }

        if( isset( $address_data['addressLocality'] ) && $address_data['addressLocality'] != '' ){
            $address .= "<span itemprop='addressLocality'>{$address_data['addressLocality']}</span><br />";
        }

        if( isset( $address_data['addressRegion'] ) && $address_data['addressRegion'] != '' ){
            $address .= "<span itemprop='addressRegion'>{$address_data['addressRegion']}</span>, ";
        }

        if( isset( $address_data['postalCode'] ) && $address_data['postalCode'] != '' ){
            $address .= "<span itemprop='postalCode'>{$address_data['postalCode']}</span>";
        }

        $content .= "<div itemprop='address' itemscope itemtype='http://schema.org/PostalAddress'>{$address}</div>";
	}
    
	if ($event->is_premium()) {
		$price = $event->get_price();
		$currency = $data->get_option('currency');
		$amount = is_numeric($price) ? number_format($price, 2) : $price;
		$content .= apply_filters('eab-events-event_details-price', "<div class='wpmudevevents-price'>{$currency} {$amount}</div>", $event->get_id());
	}
	$data = apply_filters('eab-events-after_event_details', '', $event);
	if ($data) {
		$content .= '<div class="wpmudevevents-additional_details">' . $data . '</div>';
	}
	
	return $content;
}`