How do I retrieve my Game Center username and password from my iPhone to my Android, so I can restore the progress of my Clash of Clans app?
IPhone – How to transfer or link the Clash of Clans account to an Android device, from iOS
clash-of-clansgame-centeriphone
Best Answer
You don't need your Game Center user and password —which in any case is usually your Apple ID and password; you can link devices in-game.
From the Supercell support site, specifically "Transferring your game to another device":