Haven't played in a while, and after getting an error when I tried to update, I opted for a clean install. I've now been looking at 0.0MB / 46 GB for ~10 minutes now. GOG Galaxy updated earlier without issue, so I am unsure what is preventing the game from installing (or updating previously). I have HDD to spare. Any info is appreciated.

Go into settings>Downloads and under bandwidth headline check that "Bandwith limit" is set at don't limit bandwidth. Also there is an option to pause downloads while playing, so it will pause the download if you start up a game.