The specific steps are as follows.

1. Click Insert. In the ppt, find the "Insert" button at the top of the interface and click it to enter. 2. Click Audio, find the "Audio" button in the insert ribbon, and click it to insert a piece of music. 3. Check Play Across Slides. After inserting the audio, find the "Play Across Slides" option at the top of the interface and check it. 4. Check Loop until stop, find the "Loop until stop" option below, and check it. 5. Click to expand the options bar, find the options bar to the right of the start, and click to expand its drop-down options. 6. Click Auto. In the drop-down option, click the "Auto" option to play music throughout the presentation.