There is a lot more wrong with the Windows part:

 "On Windows machines, the Python installation is usually placed in C:\Python36," is no longer true.  All-users install is, by default, in Program Files.  Current-user install is, by default, buried somewhere forgettable in the hidden /users/USER/appdata dir.

" you can type the following command into the command prompt in a DOS box:"  It has been a long time since Command Prompt was widely called a 'DOS box'.

set path=%path%

The is not permanent, at least for non-admin user.  One can add the install dir, whatever it is, to path during installation.  Or one can use 'py -3.6'