This UnityPackage will pull in the SpectatorView specific addon files for your application using the latest HoloToolkit.
You will also need to add the latest HoloToolkit master branch for: Sharing (including the External directory) and Spatial Mapping.
This can be found here: https://github.com/Microsoft/HoloToolkit-Unity
NOTE: The latest HoloToolkit is constantly changing, so consider using one of the numbered releases in the UnityPackage directory.