In summary, this is all a matter of your site is using 2 plugins, Advanced Custom Fields and Custom Post Type UI, to set up and create content for your intended audience.
If the theme developer(s) recommended/required those two plugins and had pre-configured things set up for the theme through it, say it’s a theme for movies and they set up fields for “Actors”, “Movie Genres”, “IMDb ratings”, and all this information around the topic of movies, then it’s the theme developer’s responsibility for that potential content.
If the theme recommended/required those plugins, but perhaps you added your own custom information that you felt was important, using either of those plugins, then that’s your responsibility to also get it added to the frontend for visitors to see.
If the theme does NOT require any of those two plugins, and you added them yourself to the site, then it’s also your responsibility to get added to the frontend for visitors. You would need to potentially make use of documentation especially around the theme and Advanced Custom Fields, to find the correct place to use the correct code to display newly saved custom field information.
It may sound like I’m leaving CPTUI out of this, and to a degree I am, but that’s because we’re only a small part of the overall picture, and we’re not involved in anything that Advanced Custom Fields is doing on their side.