To do Alt + H + I on Mac in PowerPoint, download and install Accelerator Keys, then press Option, followed by H, then I.
Command: New Slide Menu
This is how to do Alt + H + I on Mac in PowerPoint with Accelerator Keys, the native ribbon and alt key shortcut solution for Mac users who get more done with PowerPoint.
Alt + H + I opens the New Slide menu in PowerPoint, displaying all available slide layouts. From here you can choose a layout for your new slide, duplicate selected slides, insert slides from an outline, or reuse slides from another presentation.