You may need to refer this to your IT team/SQL server support team. It is possible that the SQL user account on the SQL server for this user has not been mapped to the required database.
Check the user's login properties on the SQL server and ensure they have a database mapping that enables them to see the required Dimensions database.
If you or your IT/SQL team need assistance, then please raise a new case online and reference the title of this article and please include details of the user affected.
Error - 'Unable to log in to the Server...' when logging in
Updated over a week ago