I’ve been running the latest versions of Cura on my two modern Macs without issue. I have an older Mac running 10.11 as well but can’t get the latest Cura (3.6.21) to launch on it. I get a dialog from the GUI application which says simply “cura-lulzbot Error” and has buttons to either open Console.app or to Terminate.
The same happens when launching the x86 binary from the Terminal from inside the .app bundle.
I think this should work — any ideas?