I suggest downloading all you media and storing it offline. You will then be less reliant WiFi and cell phone data transfers.
For example can store all your media pCloud (details here). This privacy-friendly service supports playlists and media playback in general. You can mark media for offline use, and play them back without an internet connection.
You can also store your media in a Plex library is access from computer in your home. You can stream or take your media offline to a mobile device. Note that you must purchase a Plex Pass to be able to store your media offline.