Divi | Add Divi Buildler and Divi Library to WordPress custom post types

divi-builder-on-cpt.php

<?php

function fs_et_builder_post_types( $post_types ) {
	// the identifier of the post type
	$post_types[] = 'your-cpt';
	return $post_types;
}
add_filter( 'et_builder_post_types', 'fs_et_builder_post_types' );

// the code to make the Divi Library work is this:
add_filter( 'et_pb_show_all_layouts_built_for_post_type', 'fs_et_pb_show_all_layouts_built_for_post_type' );
function fs_et_pb_show_all_layouts_built_for_post_type() {
	return 'page';
}