Update Apple ID Settings - Unable to set-up keychain

Can anyone suggest a fix to this please, I recently reinstalled macOS Big Sur on my Mac Pro and verified my iTunes account using my iPhone, I have all the check boxes ticked except 'keychain'. I have attempted to authorise the account with my password umpteen times, and have tried the fix of signing out, rebooting, and signing in again, to no avail. Any ideas? Thanks in advance.