I have a strange start screen of Blender 2.8 on a MacOS 10.11.6 as you can see below.... I am not quite sure what is going on. It is a clean install after a MacOS reinstall. I had an older version of blender that worked fine.
Blender 2.80 requires macOS 10.12 or later, your operating system is not supported. You can still use Blender 2.79 and earlier versions, all new versions will require an operating system upgrade.