ya u need to enter in another code if it is a physical copy then you need to enter in the code on the box or in it. If it is a digital copy then findmyorder.com enter in your info get code.
now here is the tricky part do not enter this code in launcher or you will have the same thing that happened to me happen.
enter your code using the mog station found here https://secure.square-enix.com/account/app click the meteor icon not new service account! enter code there and hopefully that works.
I don't know for sure because I entered my code in the launcher and for some reason instead of applying the service to the preexisting account it made a second one under the same username.