Office Timeline does not support PowerPoint for Mac.
Office Timeline is unable to install on Mac OS’s and does not work with PowerPoint for the Mac. It can be deployed on a Mac virtual machine using desktop virtualization solutions like Parallels or Bootcamp to run Windows, however, this is not a tested scenario.
Mac users can use the web version of Office Timeline that is called Pincello by going to https://pincello.officetimeline.com/
See Windows PC System Requirements here: http://support.officetimeline.com/hc/en-us/articles/201950763-System-requirements-for-Office-Timeline