Unfortunately the oldest EOS cameras supported by that version of EOS Utility 2 were introduced in 2007 or later. When one looks at the support page for the EOS 5D Mark II with Mac High Sierra v10.13 selected as the OS, however, it lists EOS Utility 2.14.31c for Mac OS X in the available downloads, which indicates that version should run on High Sierra v10.13. It seems the last Mac OS that Canon shows with a version of of EOS Utility available at the 5D support page is EOS Utility 2.7.2 for the original version of Mac OS X. If a camera from the 'overlap' period is connected, EOS Utility 3 will be used by default for that camera, but if only EOS Utility 2 is installed, those cameras will work with it as well. Both versions can be installed simultaneously on the same computer.
EOS cameras released in the period around 2012-14 are compatible with either version. Cameras older than around 2012-14 use EOS Utility 2.x.xx, while cameras since that time use EOS Utility 3.x.xx.
There are two distinct versions of Canon's EOS Utility.
