First of all, let me tell you, the Government of India banned the Garena Free Fire in India. So, Google Play Store and Apple App Store removed the app from India. But those players who downloaded the game from a third-party source are trying to purchase diamonds using apple pay credits. As per the law, the App Store can't process any payments for banned applications. So, you need to use any third-party source like Games Kharido, the Official Garena Website for Diamond top-up.