SelfMark is not open yet. This deployment is being tested, and signing
in is limited to the accounts doing the testing.
Or sign in from your signature page
Have your signature page open, the one you bookmarked when you bought it? Scroll to "Your card is ready too" and press Set up your card. That signs you in here, with no email and no waiting, until the first link is opened at your address; after that the link is the door.
That page works on its own, signed in or not. It is still the only thing that opens billing, and nothing here replaces it.