If you want to convert Apple Music and Spotify music to plain audio formats at the same time, you may need the help of audio converter like TunesKit Audio Capture, a professional
streaming audio recorder [tuneskit.com]. With its help, you can
record Spotify music as MP3 [tuneskit.com] and convert Apple Music to MP3. Then, you don't need to worry about whether the audio formats of Spotify music and Apple Music cannot be compatible with other devices.