Same thing happened to me last month when my son traded his Android for an iPhone. On Android it was literally plug and play – install, grant permissions, done. But iPhone kept asking for iCloud username and password plus I had to enable backup first. I was convinced I was missing something until I found this: uMobix it walks you through the exact differences between iPhone and Android setup, what iCloud settings you need, and shows which monitoring features work on each platform. After reading it I finally got both phones working properly and can see messages, location, and app usage on both without any issues.