When attempting to login to FAF using the https://hydra.faforever.com/oauth2/device/verify link, it gives a webpage with an error "I'm sorry. but your browser is not supported" error. This happens using Firefox or Chrome.

Attempting to click Play Offline fails with an error:
Uh Oh!
The game could not be started.

This happens because the game directory is not in the C : drive, but on D :
However, there does not appear to be any way to change where FAF is looking for the game.