https://www.mixcloud.com/developers/widget/#footerwidget
The autostart.js script will cause the main feed to start playing. This is dependent on the browser settings.
Chrome - click on media preferences in location bar (next to site address) and select allow audio and video.
Firefox seems somewhat less willing to autoplay.
Unpack this to a directory. It'll need to be running from a webserver. Simple way to do this is