RFB: Contact Identity

When a bidder is accessing the bidding record from the Bidding portal, I could see no way to show the identity of the bidder's user account. I've tried adding a User PK in hope that I can at least capture the logged in user's name. However, since the bidder accounts are not managed in Unifier, the picker does not work. There also seems to be no way to auto-populate fields based on the bidder's account, e.g. Contract Company, First/Last Name, etc. Can anyone help confirming that this is really the case?

Thanks.