Google is your friend here…
From ux themes site: https://docs.uxthemes.com/article/221-how-to-enable-ux-builder-for-custom-post-types
/**
* Code goes in theme functions.php
*/
add_action( 'init', function () {
if ( function_exists( 'add_ux_builder_post_type' ) ) {
add_ux_builder_post_type( 'custom_post_type' );
}
} );
You’ll want to change ‘custom_post_type’ to your actual post type.