1. Don't post your email in public forums, no one here can help you.
2. You've already activated the key on another account, as the message stated. WW2 can only be played via Steam and you've already activated the key, the one-time use key, on your other account. Log into your other account to play the game. You will not be able to re-redeem the key or get the game for free on this new account, licenses are all account-bound now.