The VR Plugin does work with AppGameKit Studio for me.
Put the AGKVR folder into the Plugins folder of AppGameKit Studio (in the steamapps path). The AGKVR folder should contain the Commands.txt, Windows.dll and Windows64.dll files.
In you project root folder, place the openvr_api64.dll and rename it to openvr_api.dll. NOTE: this was the one thing that stopped me from getting it working, once it did this, everything worked.
Place the steam_api64.dll as well.
Install SteamVR and run it stand-alone to make sure it works.
If you're using Oculus then you need the Meta Quest Link app installed and running.
Build and run your app.
AGK Studio copies the Plugins/AGKVR folder to the root of your project, but without the Commands.txt.
If you have a headset plugged in and active, it should fire up SteamVR and take you to the app.
if you don't have a headset attached, you get the "Unable to init VR runtime: Hmd Not Found Presence Failed (126)" error, followed by another error, then your app will start then throw another "Unable to init VR runtime: Hmd Not Found (108)". SteamVR should start up and complain about "Headset Not Detected".