Streaming Music

Is there a way to stream music to my cell phone (Android) when I’m outside, off my wifi?

I know I can play a song using the MyCloud OS5 app, but what I’m looking to do is play playlists as well (M3U).

Try to using Plex

Yes, you can play your playlists on your phone outside, use an app that can play M3U playlists and connect to your MyCloud from anywhere.