Yes! Vevox can work from a Mac as well as from an iPad. Make sure you use present view to present your polling. Present view gives you full access to all the Vevox functionality.
If you also want to incorporate a PowerPoint deck when presenting from a Mac computer, make sure you switch between present view (for polling) and your PowerPoint slides. You can hide the present view by minimizing it and switching over to your PowerPoint presentation on screen share. Unfortunately, the PowerPoint add-in does not currently work in PowerPoint for Mac.
For more information on present view read this article or watch a short video.
If you already have a PowerPoint slide and want to alternate switching between the Vevox web browser (for the questions) and the PowerPoint slides (with other information) - have a look at how the University of Warwick moves between 2 desktop versions on a Mac.
Move down to number 1.5 - Instructions for Apple users.