iPad not charging in car

I plugged my iPad into my Mazda MX5 with a USB to Lightning cable. A message popped up saying I needed an accessory to complete the connection. I clicked ok and it took me to the App Store. But I didn’t have an internet connection and it failed. I connected to my iPhone mobile hotspot and now can connect to the App Store. But I don’t know the name of the app. I tried restarting the iPad but that didn’t help. In the upper right corner it says “Not Charging”.