I have the same issue. I can't use the new site to pay, just get a screen that says "Loading", then it eventually says Error:
*Edit* OK, I think I see how to pay. You have to go to creators, and then click the one you want. The billing page should probably not just say Error when you don't have any subscriptions, but this is in alpha stages from what I understand so the more bug reports we file the better it'll get!