I solved the problem!
Essentially I had an old installation of the Build Tools present on my system, so when I installed Visual Studio 2017 I then had a duplicate build environment that was lacking the correct windows SDK (because I had been a dummy and installed the windows sdk into the build tools instead of vs2017).
So I uninstalled the Build Tools via the Visual Studio Installer leaving only VS2017 installed.
After that I removed the
CL= environment variable entirely from my system and added
C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Tools\MSVC\14.16.27023\bin\Hostx64\x64
PATH environment variable so that
cl.exe could be executed from anywhere.
From here on it was following the video guide basically.
I added the
Windows 10 SDK (10.0.16299.0) by modifying the VS2017 installation in the Visual Studio Installer.
Then I opened the HISE standalone project in projucer and built the HISE.exe as per the video instructions - this time no warnings of mac files detected!
And finally I ran HISE, added a sampler and an empty UI, exported it as VST3 64bit and success!
Now I can go back to actually making my instrument