My understanding of infinite scrolling is that you show a certain number of something. Then when the person viewing your page scrolls down near the last on then you use AJAX to get more results and insert them into the page.
Since what you’re showing are not posts, but related posts from a post object field I think that you’re going to be mostly on your own.
I’d start here: http://codex.wordpress.org/AJAX_in_Plugins
Welcome to the Advanced Custom Fields community forum.
Browse through ideas, snippets of code, questions and answers between fellow ACF users
Helping others is a great way to earn karma, gain badges and help ACF development!
© 2022 Advanced Custom Fields.