7TV installed itself on AppleTV 4K
On tvOS 10 and later you can enable the feature called "Automatic Downloads" - it sounds like this is what you did.

When "Automatic Downloads" is on, the Apple TV will automatically install apps that you have on your iPhone, iPad or iPod Touch, that are compatible with Apple TV. The key is that the same Apple ID account is added to the Apple TV as you have used on another device.