The FAQ (which you have read?) says: "Check your spam folder if you do not receive it. If you still don't receive it, try clicking "Register now" again to repeat the process."
I have needed to do that once some time ago myself.
You said you checked the spam folder. Did you also "try clicking "Register now" again to repeat the process" and were you asked for your email address to register it?
If that does not work, contact VEGAS Support. A user-created visual tutorial here.