OS X encompasses Mountain Lion > El Capitan.
You should verify the version of the EOS Utility is correct for your OS.
The firewall is pretty much the same. Open system preferences, then Security and Privacy. Now look at the tabs General, Firewall and Privacy and allow what is being blocked.
~Rick
Bay Area - CA
~R5 C (1.0.9.1), ~R50v (1.1.1) ~RF Trinity, ~RF 100 Macro, ~RF 100~400, ~RF 100~500, ~RF 200-800 +RF 1.4x TC, BG-R10, 430EX III-RT ~DxO PhotoLab Elite ~DaVinci Resolve Studio ~ImageClass MF644Cdw/MF656Cdw ~Pixel 8 ~CarePaks Are Worth It
