Login problem after closing the app

Hi,

I hope u guys are having a great day. I have a problem logging in on Khan academy kids app. I'm using a teacher account on a SMART interactive board. When I reinstall the app, I can login at first, but after I closed the app the problem occur again, and it seems that the settings that I applied before closing wasn't applied ( Teacher only device setting ). The interactive board got android 8.0 build in but doesn't have Google play service.

Thanks before.