I recently (exactly 2 hours ago) bought a (prepaid) membership card. I redeemed the code, but when I logged on, I was given a pet but I was not able to access the realms that come with the membership. Also I did not receive the crowns. There is no way to get my money back, seeing as I have already redeemed the code and was supposed to receive the membership. Fix the issue as soon as possible, please.
When you buy a prepaid card, you get membership OR crowns, not both. As far as the worlds you can access that would depend on how far you have progressed in the game. For example, the mooshu door will not show until you get to mooshu in the storyline. You can however port to those areas if a friend is there.
You can tell if your membership activated by checking your account page on the main site, or the absence of that "upgrade now" icon on the top left of your game screen.