Okay I figured it out. After doing some research, I found this website: https://secure.square-enix.com/accou...est=mogstation.
It will ask for your se account info and there will be a button that says add platform. When you push that it will bring up a screen to enter your activation key from amazon. The key can be found by going to your account on amazon>Your Games and Software Library. there will be an icon underneath the picture and title of the game that says view product key. click that and type the combination of letters and numbers into the boxes on the mogstation website. confirm the code and a little message will say your awesome or something and you should have your items in game. Bammmmmmmm =] hope this helps