Cant Display Second Featured Image In Post

Hi, i couldnt show the second featured image in custom post type. In admin panel i can see the second featured image but not in post. Documentation says paste this code but it didnt work:

if( class_exists('Dynamic_Featured_Image') ) {
     global $dynamic_featured_image;
     $featured_images = $dynamic_featured_image->get_featured_images( $postId );

    //You can now loop through the image to display them as required
 }

Do i have to do something different for custom post type?

https://wordpress.org/plugins/dynamic-featured-image/