Mac officially supports Thunderbolt3 since OSX 10.12.
https://support.apple.com/en-us/HT207266
Your Mac must be running macOS Sierra to work with the Thunderbolt 3 (USB-C) to Thunderbolt 2 Adapter. Since the new release date for OS X 10.11.6 is similar as macOS 10.12, you can connect ARC-8050T3 using Thunderbolt 3 (USB-C) to Thunderbolt 2 Adapter under OS X 10.11.6
https://en.wikipedia.org/wiki/OS_X_El_Capitan
https://en.wikipedia.org/wiki/MacOS_Sierra
Tags: ARC-8050T3, Mac, Thunderbolt3