If you're listening on the Audiomack mobile app and proceed to open another app on your phone, and the Audiomack music stops when the other app is opened, it's because the second app opened is taking over the audio on your device.
Your device can only use audio from one app at a time. Maybe listen on another device via Audiomack.com?
If your music is stopping on the Audiomack app, and it's not when you open another app on your phone:
Android users follow this link.
iOS users follow this link.