Word for mac: shortcuts to access Quick Access Toolbar and Ribbon
Unfortunately, the Mac version of Office/PowerPoint doesn't have nearly the number of shortcut keys that the Windows version.

However, On Mac, The option key on many Mac Keyboards are double-labeled Option / Alt. Try Holding down option Key in place of the alternate key.   On a Laptop Machine, you might have to use the Fn (Function key) then the rest of the shortcut.

If the above suggestion doesn't work for you, it's likely that you've run into shortcut keys that just don't work on Mac.

Other Alternavites are:


Alt Key Shortcuts on Office for Mac
Shortcut key on Words for Mac
Shortcut key on Excel for Mac