The easiest route would be to use a CoolStream adapter ( It’s a Bluetooth adapter that you plug your 30-pin connector into. You can sync any mobile device to it (Apple, Android, etc.) and play music from the device - actually you can have two devices synced to it at the same time). Here’s their product page with video of it operating on a 2013 CVO: https://coolstreamrocks.com/faqs/will-the-coolstream-carpro-work-with-2013-harley-davidson-cvo-road-king/
If you don’t want Bluetooth, you can get adapters: if you have an iPhone, just get a 30-pin to Lightning adapter that supports audio/video (the cheaper ones don’t support this), if you have an Android, get a 30-pin to USB-C (or whatever connector you might have on an Android - again, ensuring it supports audio/video).