Here's an example of how to use the download service:
download.g3v.co.uk/track/79qPDRmHmJ5xcU7oyS8CQ1
In this example, the Spotify ID 79qPDRmHmJ5xcU7oyS8CQ1 is used to download a specific track.
79qPDRmHmJ5xcU7oyS8CQ1