In case you bought the TESO from steam and having problems with connecting your steam account to your ESO account, I have found a work around.
Check your TESO launcher version. If it isn’t 1.3.6.1380697, there is your problem. It’s the wrong version, for some reason.
Download the below folder and replace your existing Launcher folder with it. Re-launch the game and when you click Login, you’ll be directed to the connect your account page.