Quote Originally Posted by Neri View Post
Did you use those 16 digits code on the redeeming site to get your 20 digits item code ?

this is the redeeming site for the code from amazon.

https://www.ffxivredeem.com/
This right here is likely the issue. The code amazon sends you is for that site, which in turn will email you 3 separate codes that you can enter into the mogstation.