Neighbor devices are the devices around you, such as your mobile phones, tablets, or your PCs. If those devices has an app with the 'neighbor devices' feature, all of them are neighbor devices. Some of them can serve others, say, sharing files. So, other devices can download files from the server devices.
Note: Some of the users said the app couldn't be started. If that's the case of yours, please tell us your situation.
Now, go to the client side -- your mobile devices.
Swith to the "My" view and tap "My Home Network", it will show the available devices. If not, please tap the ping button at the bottom-right corner of the screen. Just tap into the listed neighbor device and it will show the files shared from that device. Select "Download" to get the file.
If you have any problems, please feel free to feedback us.
If the app "HomeHub" cannot be used, you can setup your own web server in your PC. The web server software can be nginx, mongoose, etc. I will describe it later, or you can google/bing the tutorials for how to setup a web server. After the web server is ready, now you can download the mp3 file in your mobile phone, go to "My" -> "My Downloads", select the "Add Download" and input or paste the link.