Have you tried nothing at all, in either place?
Or ' root ' for username, but leave password field blank.
If that works, you MUST set your own password as that'll give a hacker complete admin access to your box.
p.s. Or maybe even find where in the menu's you need to setup a password, and add a new user with a password. Then it should work for HTTP authentication.
Found that user name is root and also found a place to enter a password