There is no native gc controller support. You'd have to install a another 3rd party software that converts gamecube inputs into readable mapping for windows (d-input).
That's not true. Just go to options, controls, click "change" top right, and press any key on your controller. Then you can configure the keys. It works with every single controller, even my bootleg SNES controller.
If you're referring to the usb controller, then yes you are right. However, if you're using an OG gamecube controller using the adapter to play on said PC, then no... it wont be able to the inputs properly without some sort of mapping software
