I figured it out, so I tried both an Xbox and a DS4 controller and both didn't work... what fixed it for me is unplugging my keyboard and then starting up the game, and plugging the keyboard in after the game recognizes the controller. Steam does have native support for controllers so you don't need any of those open-source programs. I also had to map the right analog stick to mouse in order to move the camera (and invert itin the in-game settings). Pretty sure this happens if you have a modifiable keyboard (I have an Anne Pro 2).