The user information being referred to is the name and password you are entering. The error message is informing you that you do not have privileges which can be proven. Make sure you are entering your AppleShare user name and password exactly as it was set up with the AppleShare Admin application on the server. Also make sure your user's login is enabled with AppleShare Admin.
This error can be recreated by just entering the wrong name and password when trying to configure the At Ease server for the first time.