Download the InsiteVR Desktop Application from the downloads page here.
The desktop app comes included with the InsiteVR Revit Plugin. After you've uploaded and processed a 3D model, you should use your Desktop App to view your project in VR in the Oculus Rift, HTC Vive, or Windows Mixed Reality Headset.
If you're using a GearVR, you can use the Desktop App to stream what is being seen in the GearVR to a computer or monitor. You can also control the GearVR viewer from the computer using the desktop app.