After start up one automatically logs in. Since recently (last maintenance) I very often has to force quit ESO as it is stuck on the loading screen here.
I experienced this too last night (PC-EU). Logged in - I guess? - and the game just hung there without loading any characters. I waited 5 mins or so while I did other stuff around the house, the killed the process with the task manager; next login was fully successful.
Sometimes players will experience a long wait time after logging into their account before the character selection appears. Our FAQ below has a few steps to try if the character screen is not coming up.