I defined several custom fields using ACF, which are by default displayed in the “Add new post” WP admin page. I would like to achieve something like this – when user hits the Publish button, the post will not be immediately saved, but instead, a modal popup dialog will show up with those custom fields, so the user will be forced to fill them up, and only then the post can be saved.
Please, how should I approach this? (Sorry, I am quite new at both WP and ACF).
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 🙂