On your Mac, go to arduino.cc, click on "Software", then under the Download Options section, click the link for the Mac version for either Intel or Apple Silicon.

Today Arduino has announced the availability of the new Arduino IDE in the form of version 1.6.8, which is now available with updated cores for almost all supported platforms including : AVR 1.6. ...

The new Arduino IDE 1.6.2 features a one click install of boards and libraries and now includes two new menu items in the form of “Sketch > Include Library ...