I tried from my Windows 10 PC and, after enabling file server on ENET1 (but you already did that since you got password request), I was able to connect using admin user.
I am connecting from a Windows 10 PC, are you using a different OS on your PC or a different user account?
This is quite strange, because your PC was anyway asking for username/pwd. Maybe PC was caching this information locally and prompting before actually trying to connect to the server.
Is anyway good to know that issue is now solved.