Just make sure after you download the software, to go first to "LOGIN" and then to "SIGN UP NOW" link.
Because they also have link "Join BetUS.com" which actually lead to their Sportsbook/Casino page, which is separated from Poker account.
I made a quick instruction page at:
http://www.poker-boss.com/freerolls/betus10k.htm for all the details about registration.