@Morphina You'll have to wait until Retropie supports the latest version of the Pi OS which is Debian 11 Bullseye. I checked the Raspberry Pi website and they don't offer the 64bit version of Debian 10 Buster of the Pi OS anymore.

@Ashpool I helped a few in the Bullseye-related threads but I was told not to do that anymore because the development is not finished which makes sense.