After he stormed the tractor and was taken captive, Finn defected to our side.
As a trustworthy ally, Phil showed Finn all the controls and gauges so he could operate the machine.
After his failed attempt at driving the tractor, Finn decided to downgrade to a simpler vehicle. This one doesn’t need to be steered. It just goes forward and back. Very easy. Please don’t run over Pac-Man!