Mine and sons iPads are linked..

[Thatflyerguy]

Problem: Account not linked

You may see a generic name like Player2206505872 and a message such as: “Account not linked to Game Center” (or Google Play) When this happens, your saved progress appears to be gone — but don’t worry, your account has not been reset, and your data is safe on our servers. Why does this happen? World of Airports uses Firebase Authentication to connect your account via: • Google Play Games (Android) • Apple Game Center (iOS) S…

I believe you do want to click through the warnings to relink the account