PowerPoint problems with slide advancement

I have a pre-recorded narration and want to advance the slides with the narration. I am using macOSMonterey 12.3, using PowerPoint 16.59, and of course I am using an iMac.  I have gone to the Transitions tab, and checked the After box, and put in the seconds in the Duration section.  However, the slides will not advance.  I started the file from scratch twice to see if it will work, but they will not advance.  What is the problem? How can I make the slide advance with the narration.