Testing on your ATV4 from Xcode is done wirelesssly via wi-fi.
Confirm that Xcode 9.3 is installed on your mac, the ATV4 is updated to latest tvOS 11.3, and that they are both on the same wi-fi network.
- Navigate to Settings>Remotes and Devices>Remote App and Devices on your ATV4.
- Go to your mac and use Xcode's Window menu >Devices and Simulators..you should see your ATV4 in the Discovered list on the left.
- Click on the Apple TV Icon in Devices panel... it will ask you for a Pairing Code that is displayed on the ATV4.
- Enter the code and Xcode should begin pairing with the ATV4.
When the process completes, your mac will show up in the Remote App & Devices screen on the ATV4. The ATV4 will show up on the Devices & Simulators window of Xcode.
A properly configured tvOS app should list the ATV4 as a device you can build to in Xcode's run scheme pull-down menu.
Thank you, that worked!