iPod classic and iTunes music not recognized in GMC truck

I just recently got a new truck(GMC) and it will not recognize my iPod classic. I have my whole iTunes library on it and would still like to listen to it in the truck. I have tried to add music to a usb drive but it still doesn't work. I spent a lot of money on iTunes to now have music I basically can only listen to from my computer.

has anyone ran into this and if so how did you remedy it?

Thank you.