I had the same problem, but tried about 10 minutes later and it went thru without a problem. I think things are just a little hectic at cryptic right now. I would open a ticket now about it just so there is evidence that you tried before the deadline, but you'll probably be able to get it after a few minutes. (Just close the ticket if you do get it to work!)
heck if i payed for a lifetime subscription i would just sit tight because i know that when games like this launch its bumpy right from the start, but later on down the road you will be happy that you got the lifetime instead of throwing it away because you were mad about not being able to play durring headstart.