It should have emailed you to the email you used with your purchase. Maybe check spam and junk folders of your email. Check your PayPal email address account if you paid with PayPal.
And you can download the game here: http://dof.reverieworld.com/download.php
However you would need a CD key that you would have gotten with your purchase.
If you can`t locate your CD key and can`t find the purchase email, contact email@example.com
and they`ll fix it for you asap.