What error are you getting?
Did you try passing the domain in the request as well? Username should be exactly the same as if you’d be logging in from the website (I know you both know this, but obvious things are sometimes easy to miss).
You could direct call the needed API (without any previous authentication step) if you are logged in on the machine with the AD user (and the user is imported in orchestrator, has permissions, etc). This solution works by default only with HTTTP request activity from Studio. For other third party tolls, some previous configuration must be done.
Also, it should work also with token, but maybe you should try domain\username instead of domain\username
Try and let me know if any solution worked for you.
I have the same issue.
Not able to authenticate when using AD Windows login. I tried logging first into Orchestrator and after executing the request for getting Assets from Studio, and the response is “You are not authenticated”.