iOS 13.0 he can’t download software update

Looks like you are using an older model iPhone that cannot be updated to iOS version 13/14/15. The highest version that you are probably on is iOS 12.5.5.

That app will not run on your older model iPhone. Contact the developer to see whether they have any plans to accommodate older iOS versions. I doubt it that they do but you may ask. Outside of this there is no other way to make that App run on your iPhone.

Axel F.

Which iPhone do you have and which iOS version is running on it?

Axel F.

That app with UPI guidelines is not going to run on your iPhone 6. That app needs iOS version 13 or above (iOS 14/15). Your iPhone 6 can only go up to iOS version 12.5.x.

Axel F.