I had the same problem. I was able to login for a time and now am unable and led back to a screen for a new user to enter the PIN (which of course I threw away because it said you would only need it the one time)
I sent an e-mail via a link at the site and someone e-mailed me back with a user name or password or something for the WDW site, I think.
I kind of gave up on it. One of these days I'll call member services. I just haven't gotten around to it.