DIVI builder plugin not showing up?

Add this to the functions.php file in your child theme’s folder

<?php

	function my_et_builder_post_types( $post_types ) {
		$post_types[] = 'fullpage'; 
		$post_types[] = 'fullpage-section';
		$post_types[] = 'fullpage-slide';

		 return $post_types;
	}
	add_filter( 'et_builder_post_types', 'my_et_builder_post_types' );

?>

Source: https://www.elegantthemes.com/blog/divi-resources/how-to-add-the-divi-builder-to-custom-post-types-divi-nation-short