Selling a mac
So I recently sold my 2013 imac running Catalina. I followed Apple's step by step guide here: https://support.apple.com/en-ca/HT201065
After deleting everything and reinstalling, it all came up, I made a new user account for the person I was selling it to and all was good. However, the person I sold it to is contacting me saying they cannot login with their apple ID and see the below screen. How do I resolve this and hopefully this is something that can be done remotely. The imac does not appear in my devices any longer.