Welcome to the forum Mark!
Did you make sure to set the audio settings (per the readme for the node)?
did you try - outside or NR - to play audio?
what file format did you send to the node?
What version of Node-RED and node.js are you running (take a look at the NR startup log to get this)
I just tried it and it works for me.
Please export your flow and attachet to a reply:
In order to make code readable and usable it is necessary to surround your code with three backticks (also known as a left quote or backquote ```)
```
code goes here
```
You can edit and correct your post by clicking the pencil 
icon.
See this post for more details - How to share code or flow json
