1) Download the auto_rigger folder from the home page.
2) Put the auto_rigger folder into your maya scripts folder .
FOR WINDOWS
C:\Users\put_your_user_here\Documents\maya\2019\scripts
FOR MAC
Library/Preferences/Autodesk/maya/scripts
(your path will be different, but it defaults to your documents folder)
3) In a python tab of the script editor run:
import auto_rigger.guis.auto_rig_gui as ar;reload(ar)
gui = ar.AutoRiggerGUI()
gui.init_gui()
4) Follow the instructions on Tool!
Currently the tool only works with biped characters (2 arms, 2 feet, 0-5 fingers and toes, and a head)