Please help, having trouble with photos permissions Mac

RT is not showing my photos.
I have macOS Big Sur 11.1, I’m using RT version 5.8 and I can’t figure out how to give RT permission to access my photos. I already have set the permissions to “Full Disk Access”. However, Photos app doesn’t have how to add RT application to give permission to access it, it just doesn’t show the ‘+’ icon to add a new app to access the photos, not even when I open the lock.
I’m super new to Mac, so please don’t assume that I have knowledge of all the commands.
Thank you!

5.8 doesn’t support big sur, you’ll need to try a development build.

Oh thank you. Where can I get a development build? Do you know whether the next version will?
Many thanks! :grin: