Eos utility automatically opens when I connect the 5DIII to any of my Macs with the latest operating system, and I can download to it. But, it is a bit flaky so I quit it and download to iPhoto. I haven't figured out how to extract RAW files directly from iPhoto so I use Spotlight to locate the .CR2 files, then transfer the ones I want to a folder to be opened by PS for processing.
However, I am not using the Eos utility that came with the disk for the camera but my old version, which I updated with a download from Canon to make it compatible with the latest MacOS. Maybe your Eos software is an old version. Look for the update on the Canon site. I updated some time ago and recall it might have been difficult to find and I found the right link by Googling for it.
5D IV, 5DS R, 7D II, EOS-M, Powershot G3 X, 400mm DO II, 300/2.8 II, 1.4xTC III, 2xTC III, EF 1.8 STM, EF 70-200/4 IS, EF 24-105, 15-85, 100-400 II, Sigma 10-20, Sigma 150-600mm C, EOS-M5 15-45, f/2 22, 11-22, Samyang 8mm f/2.8 fisheye