I don't think carplay will work through the hdmi adapter from apple.
you either have carplay via usb1 or app radio via apple a/v adapter. can't have both. Also note, when you have apple a/v adapter hooked up, the usb port is used for charging only, the head unit will not connect thru the usb to lightning, and if you hit usb1 while hooked up this where are you, it will give you an error message, "not a compatible device". You have to understand, the apple digital a/v adapter separates the audio/video and sends thru hdmi to head unit. charging is thru lightning to usb, no communication, head unit communicates to iPhone thru bluetooth.