Why is my dad's credit card showing as failed on my iPad Air 3?

Why does my dad's credit card say it's failed or declined? You know, I had been removed from the Apple family group by my dad, but suddenly, my Dad was going to put his credit card on my iPad Air 3, however. The worst part is that his credit card says it's failed on my iPad Air 3. I don't understand what happened to it, so that's the problem where it says failed whether I'm on the family group. Still, I don't know what happened to it, so my mom put in her credit card, but it didn't even work for hers too. It's like being stuck on a tree, but worse than I thought; you know why I've been stressing a lot and why's my iPad Air 3 is incompatible with it. Can somebody please explain how this happened?

[Re-Titled by Moderator]