Hi @greyman
I’m afraid this needs advanced code and understanding of ACF, WordPress, and Javascript.
WordPress has the ThickBox feature that you can use to show a modal popup. This page should give you more idea about it: https://codex.wordpress.org/Javascript_Reference/ThickBox.
I think you can create a ThickBox and move ACF’s fields to it. This page should give you more idea about it: https://www.advancedcustomfields.com/resources/moving-wp-elements-content-editor-within-acf-fields/. That article is talking about moving WordPress element, but I believe you can do the opposite thing too.
If you’re new to WordPress and don’t have time to learn it, I suggest you hire a developer to help you out with it, and I’d recommend looking for one on https://studio.envato.com/, https://www.upwork.com/, or https://codeable.io/.
I hope this helps 🙂
