Have you recieved a mail from Arturia about a successful registration of the reverb? Perhaps you have'nt, if the reverb is'nt on your account, as you say. I also assume you have tried to activate, if you have a activation button, but still it can't activate, if the product is'nt on your account, and if you have'nt recieved an activation code to enter manually.
If you have'nt recieved a mail, then perhaps you should try to repeat the whole process, if you have'nt tried that yet.
If that does'nt work, then i suggest you contact Arturia. Perhaps there are something wrong with the web services then.