ATEM TV HD8 ISO - Play lengthy recorded audio over a still

How do I do it?

I have a very simple setup:

Cam 1 = live video and speech (audio via wireless Sennheisers into camera XLR)
Cam 2 = live alternate shot
Cam 3 = live alternate shot
Cam 4 = PowerPoint presentation from PC

All works fine.

But I want to play background music over a still or one of the PowerPoint slides while the meeting (Zoom) is yet to start and delegates are joining, or during an intermission. I have MP3s or WAV files of some professional musicians for this.

Sounded simple to me, but it doesn't appear to be easy to achieve. I put the audio file into the media player thinking I could put a still into Clip 1 or 2, put the wav or mp3 along side it; put MP into Program and away we go. Looping forever. Obvs not.

How can I do it?

Thank you,
Charteris

Found a solution: embed the audio in a PowerPoint slide containing the image. Works.
A bit clunky, as you get a cut rather than fade on ad hoc transition. But it works.

Thanks,
Charteris