Unable to add a card in my Apple Wallet

Here are general instructions→Set up Apple Pay - Apple Support

Specific reasons you may not be able to add a card:

• Apple Pay is not supported in your country
• The card you want to add does not have a billing address in your country of residence
• The card issuer does not participate in Apple Pay

There are other more obscure reasons, but these are the most common ones.

See the following Apple articles:

Set up Apple Pay -> Set up Apple Pay - Apple Support

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 does not approve or decline cards for use with Apple Pay. If your card was declined, contact your bank or card issuer.

See -> About billing for Apple subscriptions and media products in India

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

See -> Payment methods you can use with your Apple ID

Payment methods you can use with your Apple ID – Apple Support (UK)

India

• Apple Account balance (from adding funds)
• Net Banking (adding funds only)
• UPI (adding funds only)

Then use / pay with your Apple Account balance, see: Add money to your Apple Account balance

Add money to your Apple Account balance - Apple Support