It appears that around the release of ACF PRO 5.12, it became no longer possible to include ACF PRO in a theme with all PRO features available. ACF still activates when included in the theme as described in ACF’s documentation, but some of the pro-only fields like repeaters are not available.
In the documentation, the “Include in a premium plugin” and “Include in a premium theme” features used to be checkmarks in the documentation which can be seen in an older version of the page on archive.org: https://web.archive.org/web/20211119185647/https://www.advancedcustomfields.com/resources/including-acf-within-a-plugin-or-theme/
In the current version of the documentation, they have changed to email icons with a note to “…please contact us to discuss the right subscription for you.”
I can’t find any note about this change in the changelog or in the support forum.
Unfortunately, your question can’t be answered here. The only ones that can explain it is the new owners of the plugin. You’ll need to contact them.