You have two options. You can connect the DJI Goggles to the USB port on your remote controller and fly with just the goggles (no mobile device). Or you could install the HDMI Output Module on your remote controller (like this) and attach the goggles to the HDMI port. That would also allow you to use the goggles and a mobile device at the same time (in case you want to look down and interact with DJI GO) or allow someone else to wear the goggles while you fly.