www.esoui.com
Same as for Windows or Unix
Addon Manager Minion (https://www.minion.gg/) works for Mac too, and if not check the Minion forum there for info how to circumvent problems on newest Mac OS versions.
https://www.esoui.com/forums/forumdisplay.php?f=183
About 95% of the addons are just scripts for the game so your OS does not matter,
Some addons provide external client files like Tamriel Trade Center a client.exe, which obviously wont work with Mac OS then.
But some other devs have provided additional Mac .dmg files for their addons too (not so many though).