huh? you don't
you need to connect the controller first before opening the game

Originally posted by Plato:

As the title states, this game needs to be played in Big Picture Mode in order for the Controller Support to work.

That requirement was done away with sometime ago but generally the controller needs to be connected first before launching the game.

Oh, probably just a glitchy cable on my part then lol But the big picture mode seemed to help.