Hook um_admin_custom_login_metaboxes

um_admin_custom_login_metaboxes.php

<?php

/**
 * Hook: um_admin_custom_login_metaboxes
 *
 * Type: action
 *
 * Description: Add custom metaboxes for the Login Form type.
 *
 * @example https://github.com/ultimatemember/ultimatemember/blob/master/includes/admin/core/class-admin-metabox.php#L1040
 * @link    https://docs.ultimatemember.com/article/983-umadmincustomloginmetaboxes
 *
 * @package    um\admin\core
 * @see        um\admin\core\Admin_Metabox::add_metabox_form()
 * @since      2.0
 * @deprecated since version 3.0
 */
function my_admin_custom_login_metaboxes() {
	// your code here.
}
add_action( 'um_admin_custom_login_metaboxes', 'my_admin_custom_login_metaboxes', 10 );