Follow the instructions in README.md
vcvarsall.bat or the vsvars32.bat files.First, make sure you have installed one of the Visual Studio recommended by the instructions in README.md.
If, after installing Visual Studio, the problem persists, then check https://social.msdn.microsoft.com/Forums/en-US/1071be0e-2a46-4c30-9546-ea9d7c4755fa/where-is-vcvarsallbat-file?forum=visualstudiogeneral. The solution is to run the setup again, and make sure that the Visual C++ feature is selected: