Setting up iCloud on the fourth-gen or 4K Apple TV (earlier models don't offer this feature) is easy. When you first turn on the Apple TV you'll be asked for your Apple ID and password.
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How to connect your Mac computer to a TV in 2 ways
To mirror a Mac to other smart TVs without Apple TV, you will need to get a mirroring app designed to work with that TV brand. For Samsung TVs, get the Samsung SmartThing app from the App Store. Turn on your new Apple device and sign in with your Apple ID. Open the Apple TV app. Make sure your device is running the latest version of iOS, iPadOS, tvOS, or macOS. The offer should be presented immediately after launching the app. If not, go to the Apple TV+ channel page where you’ll see the offer.