One of the apps that can be useful when demoing and generally seeing what’s going on in the HoloLens is the companion app.
The problem it seems for those of us in Australia and presumably other non-US countries is once you get to it in the store (as the search doesn’t yield results) is you can’t download it. Even though we can now get HoloLens in Aus the app hasn’t been updated.
To get around this – adjust your pc region settings to United States.
Go back to the store and you can download. You can return to your regularly scheduled viewing by flipping your region back to Australia