How to sync ViewportFrame camera with main camera?

Ok, so I am trying to make a Google Cardboard VR game with ViewportFrames. I am using another script to get the gyro input from the phone. But I have run into a problem. I want to sync the ViewportFrame camera with the main camera, so all rotations and movements are the same between the two cameras. Another problem that I have run into is all scripts that I have seen create new models for every movement, and I want to minimize this as much as possible, since I have a city already created. I am not creating the ViewportFrames off of scripts, and it is all seen in the explorer. I saw the camera being set up like this before, and I want to do the same. Any help is appreciated. Thank you!

Link to where I found some code: https://developer.roblox.com/articles/viewportframe-gui

Pictures: https://prnt.sc/o80lqu https://prnt.sc/o80m3y