What we see in the output above is that indeed Microsoft Visual Studio 2015 has been installed, but the actual C/C++ compiler is missing. This is likely caused by having installed Microsoft Visual Studio 2015 Professional using the "Typical" setup option which will not install the Visual C/C++ compiler by default. This is seen in Microsoft's documentation:
To resolve this issue, re-run the Visual Studio 2015 installer again and choose to perform a "Custom" setup. Then during installation, make sure to enable "Visual C++" under "Programming Languages".
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