When you install apps from outside official Google Android TV Play Store (as here: https://www.futeko.com/newforum/index.php?topic=4697.0) you will sometimes find they are not added to the Android TV Apps menu.
To get around this problem install 'Sideload Launcher' or 'TV Apps Drawer' from Android TV Play Store.
Both of these apps add an app entry to your apps menu that, when selected, gives you access to all apps installed on the system.