If you have an Apple TV with a USB port, simply plug it into your computer and Sideloadly will detect it. If you have a portless Apple TV then sideloading will only work on macOS. A virtual macOS should also work as long as you are using the same network. For macOS to see your Apple TV, open Settings > Remotes & Devices > Remote App & Devices and keep it on that screen so Sideloadly will detect your Apple TV.