I'm not sure why they don't just explain it, so here is what I experienced.
When you use Paypal to purchase the game from Players Dynasty. You get a message that the key will be sent as soon as your payment processes. Well you payment processes immediately. The issue I experienced is that the key came in a none English formatted message and I had to look closely. Being a 40 year veteran of games, I saw the key in the message. Though the other messages came to my inbox directly, this one went to my spam folder because it was not English.
Hope this helps.