I am unable to add my debit card

See the following Apple articles:

Set up Apple Pay

Set up Apple Pay - Apple Support

Set up Apple Pay in Wallet on iPhone

Set up Apple Pay in Wallet on iPhone – Apple Support (UK)

Countries and regions that support Apple Pay

Countries and regions that support Apple Pay - Apple Support (EG)

If you can't add a card to Apple Wallet to use with Apple Pay

If you can't add a card to Apple Wallet to use with Apple Pay - Apple Support

Apple Pay participating banks in Africa, Europe, and the Middle East

Apple Pay participating banks in Africa, Europe, and the Middle East - Apple Support

About billing for Apple subscriptions and media products in India

About billing for Apple subscriptions and media products in India - Apple Support

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