I don't think the app has any USB connect-ability to the car via USB. The Access app connects to the Kia servers over the Internet, and the car talks to the servers over an internal modem. It's all done over the Internet. What exactly are you trying to do with the app in the car?
Was just following instructions on setup in connecting it to the USB in the Niro. I was using the phone to activate the UVO in the Niro. With the Niro unactivated, I logged into the Kia Access app on my phone and it showed me a full screen of options but also indicated that the Niro's UVO was not yet activated. I then activated the Niro and the phone app screen would sort of freeze, i.e. I couldn't navigate anywhere else nor click any buttons. I then closed the app, logged in again, and then briefly a white screen would appear, the text "mileage ---", and about 2 seconds later the app would crash and the phone would give me an error message that the Kia Access App has stopped working. I attempted to log in several times with the same result.
Even though the Niro now showed as being active, it was not able to be accessed through the app account that I set up. Not even through my wife's phone. So at some point during the activation of the Niro and crashing of my phone app, the link to the account got lost somewhere.
Not being sure exactly what happened the first time, I called support and they deactivated the Niro. I then went through the same steps again with my phone with the exact same result, i.e. Niro activation, phone app crash, and disconnect of Niro to account. I called support again and had them deactivate the Niro again. Then I tried activating it with my wife's phone and it all executed perfectly. The Niro is now safely connecting through my account and my bad android does not have any affect on it.