I have enrolled my Mac to the beta software program but it just gave me the macOS 10.15.6 beta. I don't know what to do.
I can't install macOS Big Sur
This might mean that you are in the CustomerSeed. Big Sur has not been released as a public beta yet.
More info here.
https:// mrmacintosh.com/big-sur-beta-not-showing-up-in-software-update-troubleshooting/
More info here.
https:// mrmacintosh.com/big-sur-beta-not-showing-up-in-software-update-troubleshooting/