Here are the steps to install the Singa tvOS app on your Apple TV:
Turn on your Apple TV (4th Generation) and open the App Store
Search for the Singa Karaoke app and install it on your Apple TV
Once Singa is installed, open it and click the "Sign In" button
The app will provide you with an activation code
On a computer or mobile device, visit the activation page,
Sign in to your Singa account (or create an account) and enter the activation code appearing on your TV screen
The app will refresh, and you can start singing on your Apple TV
