At first, I directly extracted the mod files into the game folder, and it worked – pressing Ctrl would trigger the follower menu. However, the follower sprite always showed as a "?" icon. I tried to fix it but couldn't. Then I saved the game with the "?" still displayed and exited. When I loaded that save again, the "?" was still there, but pressing Ctrl no longer did anything. I tried loading a different save file, and even a completely unmodified copy of the game, but now the mod doesn't respond to any key presses at all, no matter what I do.