If you purchased the game via Amazon as we did, you are probably a little frustrated trying to figure out why you can't subscribe right now. I was too until I finally figured it out.
The first code you got from them via email was only a promotional code for early access. The ACTIVATION code is what you need.
To find it, go to your amazon account and select "Your games and software library". If you are on the main account screen you'll find it in the 4th section down called "digital content". From there you should see your ESO purchase and an option stating something like view game code or activation code. Select that. Then you will be presented with your original promotional code and your magical ACTIVATION code that you've been sorely lacking.
Once you have the activation code, go to redeem code in your ESO account screen and everything will start making sense at last!
Edited by Spuddlethud on April 6, 2014 3:39PM