If it doesn't work check the addon folder in Appdata/Roaming/Blender Foundation/2.80/scripts/addons is called blender-rigui (latest release) Addon is very much WIP ...
Auto-Rig Pro is released under the terms of multiple licenses: The add-on source code components of Auto-Rig Pro are released under the terms of the GNU General Public License, version 3. Assets files ...