I want to pay a iphone 11 by my mothers card

I live in New Zealand and I want to get a Iphone11. I ordered it yesterday by mothers card ( my mother is living Japan ) from New Zealand Apple Store. My mother’s credit card’s billing address is Japan but I couldn’t select it because it just show me US,UK,Singapore, New Zealand and Australia. Therefore I selected my shipping address( New Zealand ).. However I couldn’t pay.. Could you please tell me what do I have to do now..