A slight failing of Node.JS on Windows is that any global npm installations are not global at all! They are installed to the currently logged in user. Somewhat annoying. You could try using the Windows Ubuntu Subsystem to avoid this issue but that is only in beta right now. Not sure why you didn't have that link though as the Node.JS installation should have set everything correctly and the node-red command should work without any issues as long as you are logged in as the user that installed node-red in the first place.
Also note that the advantage of the way Node.JS works on Windows is that you don't need elevated rights to do npm -g installs.