To do Alt + A G on Mac in Excel, download and install Accelerator Keys, then press Option, followed by A, G.
Command: Group Menu
This is how to do Alt + A G on Mac in Excel with Accelerator Keys, the native ribbon and alt key shortcut solution for Mac users who get more done with Excel.
Alt + A g opens the Group dropdown menu in Excel’s Outline section. This menu provides options to group selected rows or columns together, or to automatically create an outline based on your data’s structure using Auto Outline.