Oh I see, yea the page doesn't give away too much info it just says:
Quote: "All demos have full source code in both Tier1 AppGameKit Script and Tier 2 C++
Note: The Tier 1 Plug-in has been updated so users must ensure they install the latest Windows.dll and Commands.txt files."
SOURCE: -
https://www.thegamecreators.com/post/virtual-drum-kit-duck-shoot-demos-added-to-appgamekit-vr
I have not actually purchased the VR yet myself I was aiming to do that in the near future, one could only assume they would be in the project directories ? Might be a long shot but rather than just reinstalling the AGK2 did you try this:
in the AGK2 program click Tools/Install Addition Files/Install..
Do they appear in the project directory after this ?
Also I know my DLC for app game kit usually has its own seperate directory in its steam install folder, the quickest way to get there would be right clicking the software in steam, click properties, local files, browse local files.. then there should be a folder named DLC which will contain all the DLC purchased for App Game Kit and in there will most likely be the above mentioned that you are looking for
Hope this helps
EDIT***
It seems the second suggestion was the answer as clarified above by the forum mod