As I installed the latest Beta, I noticed that the installation (install.txt) launches setup.exe instead of launching the msi installer. The issue is that HS2 will continue its startup process instead of waiting until the installation is done, potentially loading earlier versions of this plug-in while you try to install it at the same time. In my case, the installer got stuck (db lock I believe) and had to kill both HS2 and the installer, plus install the plug-in manually.