1 - Sign out and sign back in to both the Creative Cloud Desktop app and the Photoshop (beta) app 2 - Log into Behance with your Adobe ID and enter your Date of Birth. 3 - If you sign in using social sign-in (Apple, Google, and Facebook), ensure that your date of birth in that account is set to public instead of private.
Once yourDate of Birthis up to date, relaunch the Photoshop (beta) app to enable Generative Fill.
p.s. i don't think the adobe website, and forums in particular, are easy to navigate, so don't spend a lot of time searching that forum list. do your best and we'll move the post if it helps you get responses.