Spotify is a nice choice. But I don’t know whether Spotify app is interval music for Simbian Mobile Disco. Spotify allows free users to access to its music library. So you don’t need to pay for it, like premium streaming music services, including Apple Music, etc.
If it doesn’t match it. You still don’t need to worry about this issue. There is still a way to fix it by using AudFree Spotify Downloader Mac to download and convert Spotify to Simbian Mobile Disco compatible audio formats.
Of course, anyone has his taste. My style is here.