Apple does not accept payment on Apple Card MasterCard. Goldman Sachs Bank is the issuer and servicer of Apple Card accounts. Goldman Sachs considers payment by check as non-conforming and may refuse acceptance of a check if the account owner does not call and verify acceptance of a check with an Apple Card Specialist.
You can make an Apple Card payment online at card.apple.com.
If your iPhone is missing or stolen, you can contact Apple Support to make a payment.
If you set up Apple Cash and verified your identity, you can use Apple Cash or your bank account to make an immediate one-time payment. Information on payment with Apple Cash is in the support article linked below.
How to make Apple Card payments - Apple Support
Payment by check is considered a non-conforming payment method. If you must mail a check, call first to verify acceptance. If you fail to call and verify acceptance, your payment/check may be returned and you’ll be responsible for any late payment or interest charged to your account.
CONTACTING — Goldman Sachs Bank
https://www.goldmansachs.com/terms-and-conditions/Apple-Card-Customer-Agreement.pdf