Fix for digital preorders with this problem
1. Search your email for a message from: webhelp.v4@digitalriver.com
2. Click the link that is your order number. Says "Order Number: XXXXXXXXX".
3. On the page that opens, put in your order number, and last 5 of credit card.
4. It will find your order, and there will be a 20 digit XXXX-XXXX-XXXX-XXXX-XXXX number labed "Serial Number".
5. Enter that number in the game client, or add it to the services in your square-enix account page.
6. Good to go.
The problem is that everyone used Early access serial numbers, they expired on the 27th. You need to register your permanent serial number now.
Cheers.