I am a newbie and got this working with little effort.
1.I had to enable mp3 content in Site Global Configuration.
2.Install. Then click on Extensions/plug in to enable.
3.Create article and then either insert full html:// or upload mp3 content from your computer to media manager/stories/ (create new mp3 folder).
{play}http://blahblah.html{/play}

{play}images/stories/mp3/yourfilename.mp3{/play}

Looks simple and it works - thanks to the developer.