I'm using a OnePlus 6 and have been playing games with the touchpad for several days and decided to buy the stadia controller. I'm using a usb-C male to male cable and it won't synch to the app for some reason. I can see the controller in controllers tab and it vibrates when I plug it in, but doesn't actually synch.
I switched the male to male cable for a USB-C to type A converter, and turned on "OTG storage" in settings and I'm good to go. Not sure why a Type C cable alone won't work.
https://www.amazon.com/gp/product/B07THFJ1J5/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1 This usb-c cable works and also if you have a macbook pro usb-c to usb-c charging cable that one also works. Some cables need to be reversed when you plug in from either end, phone to controller and vice versa. The one i gave a link though only lasted me 3 months of plugging in and out since i need to use my phone for calls or take it to work.
I wish we could have a more plug all the time friendly controller that we can just fold when we need to use our phone without unplugging the controller like the razer kishi. also a good alternative