I also see that there is still some way to go with the new setup till usable for us again.
From what I understood the account must be present as a windows login name so ISS (the
webserver part of windows) can authenticate the user.
So in theory you could try to add the account locally on your TMS. But yea, its not really
suitable for a mass deployment as passwords will get out of sync, lots to maintain in parallel, ...
Maybe thinking about skipping this feature for now or investige to set up an AD for TMS could be ways to go, ... :-(