The remote user ID of a user is the value from the user directory (e.g. Active Directory), which ensures the mapping of the Haiilo user and the user account from the user directory.
Which value is stored there, you define in the configuration of the user directory in Haiilo Home. There you define an attribute under "User" as "User unique ID".
In the user directory, this ID can be checked for the example shown above, e.g. in the attribute editor (or via PowerShell) of a user.
If these values are different in Haiilo Home and on the user directory, the user is considered orphaned. And therefore cannot log in anymore. By correcting this value, local users can also be made remote users (you can find more information about this here).