Hey Tania Gougler,
We’d be happy to help out. Sounds like you’re having issues with songs playing continuously during use of CarPlay.
To get started, restart your iPhone. If the behavior persists, check to ensure that you have a strong reliable data connection while playing music. If you don’t, this could be why it’s pausing after the song, because it’s not yet able to load the next song to play.
Since this is occurring with a third party app, Amazon Music, we would also suggest following the steps here to isolate any issues with the app itself. Please note that it is suggested to contact the app developer if these issues persist after completing the recommended troubleshooting: If an app on your iPhone or iPad stops responding, closes unexpectedly, or won’t open - Apple Support
Take care!