Tschuß,
Is it possible your Steam account is already linked to another TERA account? Is making a new Steam account an option for you? I was having this issue because I borrowed a friend's account and after making my own account, the link worked right away.
Do ask TERA Support via Steam if your account has already been associated with another account. Maybe you linked it to a 'guest' account without realising it?
I know it's probably not the cause but tried using another browser?
Also, how about you try the TERA via Steam launcher? If it logged you in right away into a brand new account, then you'll know what to tell Support.
... and for us!












