I am not able to add card

You cannot add a Debit/Credit Card to Apple Pay if the county that you have chosen under the Apple ID does not support it. (e.g. India)

Adding Credit/Debit Cards to Apple Wallet depends on the country that you live in --> Countries and regions that support Apple Pay

However, you may add any of the following passes/tickets

Adding Boarding Passes, Bookmyshow Tickets, IRCTC (Railway) tickets, Airline Tickets, Game Tickets and Hotel Bookings are only possible if the issuer has enabled the "Add to Apple Wallet" feature for the tickets/passes issued by them. See some examples below.

The card issuer must enable the "Add to Apple Wallet" feature.

You will find this in the Card Issue Document

1. Tap Add to Apple Wallet.
2. 

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