I was told the same thing by Apple Support for my Mazda CX-30 and my new iPhone 15 Pro. The rep said that I need to get an Infotainment update for my vehicle.
Mazda told me that it's $145 to update the software and the only way to find out if there is even an update available is to bring the car in. They also said that if there is an update for that, it's not going to be out yet since the iPhone 15 has only been on the market for less than a month now. After purchasing a $1000 phone, now to have to spend $145 just to get CarPlay to work?
I'm waiting on this until I can figure out what the actual problem is. I really don't think it's the vehicle software.
I know the iPhone 15 hasn't been out for very long now, but this is ridiculous! I expected more from Apple.
My iPhone 12 worked just fine with CarPlay.