Can you tell us which Mac you’re using? You can find the information we need in the Apple menu, under About This Mac. Just copy that information, minus the serial number, and paste it here for us.
You can get source for the engine through GitHub, and compile using Xcode on the Mac.
I downloaded it from GitHub and modified it like the link I posted said, but when I tried compiling it using Xcode it failed, saying: make: *** No targets specified and no makefile found. Stop.
Command /usr/bin/make failed with exit code 2
This chart shows that you would need to upgrade your GPU to one that supports OpenGL Version 4.1. and is the cause for the on screen display you are seeing. However, your CPU is also below spec as UE4 requires a minimum of a quad core processor 2.5 Ghz or higher as listed here:
If you are considering upgrading your system to be able to run UE4, I strongly recommend going above the minimum specs to AT LEAST an i7 processor 2.5 ghz, 16 GBs RAM, and a 2GB DirectX 11 compatible graphics card which are the specs of the MacBook Pro I’m using to test UE4 issues on the Mac.
Of course this also depends on the type of game you’re developing; If you are developing for the iphone, these specs would be fine. If you’re aspiring to work with a team to create AAA type titles for Macs, even higher hardware specs would be appropriate.