«This email belongs to another account. Sign in the way it was created, or contact the farm owner» - the address is already tied to another account. Sign in the way it was created.
«Sign-in with … is unavailable» - signing in through this external account is switched off right now. Sign in with a username and password.
«Could not verify the … sign-in» - the external service did not confirm the sign-in. Try again.
«The email in the … account is not verified» - the email address in the external account is not confirmed. Confirm it there and try again.
«No access to the external account email» - the external account did not hand over the email address. Without the address the farm cannot recognise the member.
«The … sign-in session has expired, please sign in again» - the sign-in took too long and was cancelled. Start again.