You're right. It doesn't install any files into the main game folder and sub-folders, but it installs the launcher. Maybe that gets placed in AppData. Running the launcher downloads the game's files.
Regarding the account, I used to have an account with, I'm about 100% certain (since this is about the only name and email I use everywhere on the internet), this name and email address, and neither existed when I tried to log in today, so I created a new account with the same details. I hadn't logged in for ages.
Well, looking forward to having the game up and running again soon.