1. First open the PPT presentation and click the insert option inside.

2. After clicking Insert, find the audio, click Audio, and select the background music to be inserted.

3. After inserting the audio, select the audio symbol, right-click, and click Format Object in the pop-up options.

4. After entering the audio tool, check the loop playback until it stops, and select the option to play across slides, and that's it.