having trouble using appletv app on brand new insignia fire edition tv (2019)

I pay for the appletv app and it works fine on two other household tvs. This new insignia fire edition tv allows appletv to be downloaded but continually tells me to update the software. I was on the phone tonight for two hours with a fire tv person to no avail. Then I saw this Downloader app and downloaded it, thinking that I need to update the software for the fire tv, not appletv app. But I cannot figure out how to do this. Have googled and googled without any success. Help.