Do you want to play music that loops continuously in your presentation, without any interruption as you move from one slide to another? Yes, this is a great feature but it has its caveats. Not only can a looping music audio make the audience inattentive, but the speaker will be at a distinct disadvantage too, trying to compete with the audio clip for the audience’s attention. Yet, if you are showing a bunch of successive slides that include pictures, and no speaker is accompanying the slides, then, adding a music clip to span across slides may be a good idea.
Loop an audio clip to play across slides in PowerPoint 2019 for Mac.

