Hello.
Both the Epic Games Launcher and the Unreal Engine 4 are available and supported on Mac.
However, Unreal Studio (which is primarily the Datasmith plugin added to the Unreal Engine) is not currently supported on Mac. We have a development goal to support Mac later this year.
While you are currently unable to use the Datasmith plugin on Mac, you are still able to begin working with the Unreal Engine, and you can download the launcher from here.
Cheers