After launching the game and choosing your preferred megaserver, you will be given the choice to create a new ESO account or link to an existing ESO account. Select Link Existing Elder Scrolls Online Account. Once you enter your existing UserID and password, you will see a confirmation screen.

If you have forgotten your UserID or password, you can request a password reset here.

Please note that Account Linking is for account management purposes only and does not transfer characters, crowns, ESO Plus, or other in-game items.

If you are not able to link from the console interface, you can link your account via the ESO website directly.