Script to load a datepicker that targets the custom user field with class name 'my-datepicker'

load_my_jquery_datepicker_script_for_pmpro.php

<?php
/**
 * Load datepicker script for specific pages.
 */
function load_my_jquery_datepicker_script_for_pmpro() {

    global $pmpro_pages;
    if ( is_page( array( $pmpro_pages['checkout'], $pmpro_pages['member_profile_edit'] ) ) ||
        defined( 'IS_PROFILE_PAGE' ) ||
        ( is_admin() &&
        isset( $_REQUEST['page'] ) &&
        'pmpro-addmember' === $_REQUEST['page']
        && function_exists( 'pmpro_addmember' ) )
        ) {
        ?>
        <script>
        jQuery(document).ready(function($) {
            $( '.my-datepicker' ).datepicker( {
                dateFormat: 'yy-mm-dd',
                showButtonPanel: true,
                changeMonth: true,
                changeYear: true,
                yearRange: "1920:2040", // set your start and end years for the datepicker here
            });
        });
        </script>
        <?php if ( ! is_admin() ) { ?>
            <style>
            /* Customize the style and layout for the Jquery datepicker here */
            #ui-datepicker-div {
                -webkit-box-shadow: 10px 10px 25px 0px rgba(0,0,0,0.35);
                -moz-box-shadow: 10px 10px 25px 0px rgba(0,0,0,0.35);
                box-shadow: 10px 10px 25px 0px rgba(0,0,0,0.35);
            }
            </style>
            <?php
        }
    }
}
add_action( 'wp_head', 'load_my_jquery_datepicker_script_for_pmpro' );
add_action( 'admin_head', 'load_my_jquery_datepicker_script_for_pmpro' );

function my_pmpro_datepicker_enqueue_scripts() {
    global $pmpro_pages;
    if ( is_page( array( $pmpro_pages['checkout'], $pmpro_pages['member_profile_edit'] ) ) ||
        defined( 'IS_PROFILE_PAGE' ) ||
        ( is_admin() &&
        isset( $_REQUEST['page'] ) &&
        'pmpro-addmember' === $_REQUEST['page']
        && function_exists( 'pmpro_addmember' ) )
        ) {

        // tell WordPress to load the JQuery Datepicker, the ui-core depency will automatically be loaded,
        wp_enqueue_script( 'jquery-ui-datepicker' );

        // load CSS to style datepicker.
        wp_enqueue_style( 'jquery-ui-css', '//code.jquery.com/ui/1.12.1/themes/base/jquery-ui.css' );
    }
}
add_action( 'wp_enqueue_scripts', 'my_pmpro_datepicker_enqueue_scripts' );
add_action( 'admin_enqueue_scripts', 'my_pmpro_datepicker_enqueue_scripts' );