Once I sign up, some of the resources return 403 (IP is blocked by geoblocker ...). Went through a US proxy and can see what it's supposed to look like. The funny part is that first message that is supposed to say "Thanks! You're Jet Insider No. XXX,XXXX Share to move up the ranks" instead says:

Thanks!

You're Jet Insider

No."

I could not figure out what the hell that was supposed to mean.

I guess this is just some launch last minute scrambling or something? Might not have been the best choice, anyone outside the US or wherever is being blocked has the first impression "Ah, they are going to take on Amazon and can't get a signup flow to work ... right".