Background music not working in Storyline 360 file

I am trying to add background music to a Storyline file but unfortunately this trick isn't working - the audio isn't playing. This is what I did:  

1. published the storyline 360 file (used the Web setting) 

2. copied the .wav file into the published folder at the same level as story_html5.html 

3. opened the story_html5.html file and add the following code right before </body>: 

<audio src="song.wav" preload="auto" autoplay loop></audio>

4. Ran the story_html5.html file. The audio isn't playing for me though? 

The track is about 2 minutes long, but the module is longer and interactive... so not a set length. I assume the audio should start immediately and keep looping? 

Thanks! 

Michele