1. First, open the PPT software, find and click the "Audio" drop-down button in the Insert tab of the menu bar.

2. Select the audio source you want to insert. Here, for example, select "Clip Art Audio".

3. Click the music you want to insert on the right side of the window.

4. As shown in the picture, the selected audio has been inserted.

5. Click "Play" in "Audio Tools" in the menu bar.

6. Click the drop-down button as shown in the picture.

7. Select "Auto".

8. Finally, check "Hide during show" and "Loop until stopped".