Important Details for The Elder Scrolls Online Authentication

Zenimax studio has given everyone a surprise with The Elder Scrolls Online authentication process.
To redeem your main game key for ESO you need to set up a subscription plan for your account using credit card or other payments.

You will be charged instantly for the subscription time you chose - this payment serves as authentication and will be reversed* in 3 - 10 days.

* not if you paid by iDEAL or a couple other payments - you will be stuck with an extra month, 90 days or 180 days

The Explorer's Pack - can only be redeemed after the previous procedure, after main game is activated on your account.

Good news is: early access has been extended untill sunday- customers have now a grace period to activate their codes.
Considering how much negative feedback Zenimax is getting the authentication may be dropped.