WordPress is a CMS content management system that can be used to built websites, blogs, or even app. Therefore, WordPress is not a Software that can be installed on Mac or any machine, it is basically a set of files and folder with .php extension which has some code written in PHP language, which to execute requires a server like Apache or Nginx and you can see WordPress in action on any browser. So WordPress is not Operating System dependent. Hence WordPress can work on any OS be it Mac, Windows, Linux, or any other OS, as it only requires a server.