Hi CLSmyth, RoboHelp is not available for Mac machines. If you want to use RoboHelp on a Mac machine, then you might use it on a Boot Camp or on any virtual environment like vmware, etc.
Just to amplify the response, RoboHelp only runs in a Microsoft Windows environment. So if you opted for BootCamp or Parallels, you would need to have Microsoft Windows installed as the operating system for those environments.