Note that you have to open the FLR gui on a machine backed up by VDP.
Try a local machine admin (not domain, just to be sure) for the Basic Login.
User you registered the VDP appliance with under the Advanced Login. You can check this under the configure tab here: https://VDP_IP:8543/vdp-configure/ but note that the appliance password is different still!
As another tip, I've found I have to use this format for all my Vsphere/VDP web client stuff: username@domain with no extension.