So, it turns out you have to use Origin on a PC to create a child account for each child. Then link that account to each child's platform account. It's an inane way of handling this, considering a parent is required to allow access in the first place, but that's what fixed this for me.
@Meachamus_PrimeThe fact there is zero helpful explanation in the popup boxes they give you when you fail login again is just an onboarding disaster.
I will never buy a game on Origin because of their terrible customer experience. The countless hours of life that must be lost by millions of families around the world just trying to play games they have bought.
Thanks for the advice. I'll give it a try. And then uninstall Origin straight after.
