When using Add permissions to add the user NT AUTHORITY\Authenticated Users, ShareGate displays a message similar to:
The user 'NT AUTHORITY\authenticated users (NT AUTHORITY\AUTHENTICATED USERS)' could not be created at the destination. This is probably because the user was either deactivated or deleted in the Active Directory.
NT AUTHORITY represents your local machine's system services. The token to the right of the backslash represents the internal service "users" of your operating system. Options for this token can include SYSTEM, LOCAL SERVICE, Authenticated Users, and others.
NT AUTHORITY is therefore considered part of a special group and does not exist in the Active Directory.
When the app queries the Active Directory for Authenticated Users, the special group is not found. The ShareGate migration tool then considers NT AUTHORITY orphaned, and the error occurs.
The ShareGate migration tool does not support transformations with NT AUTHORITY\Authenticated Users.