Is there a way to get a file URL from the relationship ACF field?

Question

I have a relationship acf field that displays posts from a custom post type that are then displayed on the front end.

The post type is publications and I want to link to the publications uploaded file as opposed to the single page link, how would I do this?

Here is the code for the relationship field I have:

$posts = get_sub_field('download_existing');
     $existing_link_url = '';
     foreach ((array)$posts as $link_posts) {
        $existing_link_url = get_permalink($link_posts->ID);
}

I know I am getting the posts permalink in the for each loop but I have tried wp_get_attachment_url and it doesn't seem to link through the file.

Is it possible to do what I am trying to do, I have looked on the ACF website and searched for this but I can't find anything.

Answer 1

$posts = get_sub_field('download_existing');
     $existing_link_url = '';
     foreach ((array)$posts as $link_posts) {
       $existing_link_url = get_field("your_field",$link_posts->ID);
     }

This will overite in the loop the $existing_link_url so you may want to save it.