You can run RealFlight9 in BootCamp or equiv on the Mac, in a Windows virtual machine. RealFlight9 uses DirectX, so it must have a Windows OS and drivers to function properly for graphics. RealFlight9 does not run native in Mac.
PS edit: my Mac(s) are my primary computers... those and my Linux servers|desktops. I had to purchase my first Windows machine in thirty years in order to fly RealFlight9. True story.