Customizing Links in the Post Slider & Blog Grid

I’m trying to use the post slider and blog grid features to display articles on my site.
When you click on the image or link, instead of going to the post, I want it to go to another link thats specified in a unique advanced custom field for each article. I made a child theme and set up the postslider php file but i cant figure out how to call up the custom field content.

i found two places that seem to control the link
$output .= $thumbnail ? “{$thumbnail}” : “”;
and
$output .= “<h3 class=’slide-entry-title entry-title’ $markup>“.$title.”</h3>”;

I thought I would replace the $link text above with something like the_field(‘press_link’);
but that isnt working

Also I can see that my edits have an affect on the post slider but is there something more i have to do to get them to affect the blog grid?

Any help I can get would be incredble!
I know it would be better for these to be links instead of posts but I’m ultimately going to apply this to existing site that has over 100 of these already built so I’m trying to work with the existing structure