How do you get the car AV assistant working with this Tablet style screen not having any luck

Once you have made a Bluetooth/wireless connection to the unit with your phone, you have to actually open CarAVAssist on the headunit FIRST, and then open it on your phone and make a connection. From the home screen, swipe to the source selection screen. It should be towards the bottom. Doing this disables CarPlay or Android Auto which would otherwise prevent the app from communicating with the unit.