Hi arcadia06,
Since you're having issues with CarPlay when it comes to trying to play music via Spotify through USB, we recommend that you try the steps here: If you need help with CarPlay - Apple Support
To perform the recommended troubleshooting steps via the link above, complete the steps in the section titled "Check your wired or wireless connection and your iPhone settings."
If your iPhone is updated to the latest version of iOS, follow these steps—checking CarPlay after each step:
1. Check your connection to your CarPlay stereo:
* If you have a wired connection, try connecting again with a different USB cable to a different USB port if you have one.
* If you have a wireless connection, make sure that Bluetooth is turned on on your iPhone under Settings > Bluetooth. Then go to Settings > Wi-Fi, and make sure that Wi-Fi is also turned on. Tap the CarPlay network, and check that Auto-Join is turned on.
2. If CarPlay doesn't activate automatically, look for the CarPlay logo on your car's display and select it.
3. Restart your iPhone and your car.
4. Make sure that Siri is on.
5. If your iPhone isn't detected by CarPlay, make sure that CarPlay isn't restricted. Go to Settings > Screen Time > Content & Privacy Restrictions. If Content & Privacy Restrictions is on, tap Allowed Apps, and make sure that CarPlay is enabled.
6. Go to Settings > General > CarPlay, tap your car, then tap Forget This Car. Then set up CarPlay again.
7. Make sure that your CarPlay stereo is using the latest firmware from the car manufacturer. Check your car's manual for more information.
We recommend the steps above because they will show you what to do if CarPlay doesn't work like you expect.
If you’re still experiencing the same issue, then we recommend that you contact Apple Support directly so that they can work with you to find a solution.
You can reach them by clicking here: Apple Support or calling the most local number in your region: Contact Apple for support and service.
Thank you for participating in the Apple Support Communities.
Cheers!