This sub is for devices running AndroidTV, not TV boxes that happen to run a version of Android. From my reading that device appears to be the latter. If it won't install an update it's probably not officially marked compatible in the store, you should be able to sideload either by downloading the correct APK from Kodi's site or installing an app from the store that downloads the latest one from one of the official mirrors. I used to use a guy on the store called Ollan's updater back when it was called XBMC Updater, haven't tried it since that one was discontinued and replaced with the similar app Kodi Updater, but presumably it works the same

I know of a mountain called the - K2 - not any Android TV box.