Hi sv_4321,
Welcome to the Apple Community.
Sorry to hear that it seems the App Store is not available to you in your region of India.
It seems that Apple has set up certain Apple services for use in India generally, but perhaps your region does not allow that.
For India generally:
Apple's article: Availability of Apple Media Services - Apple Support
Says:
India
- Apple One
- App Store
- Apple Music
- iTunes Store
- Movies*
- Music
- Ringtones & Tones
- Apple TV app
- Apple Books
- Apple Podcasts
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Your Apple ID is the one account you use to access all Apple services,
such as the App Store, Apple Music, iCloud, Messages, FaceTime and more.
It seems Apple requires a valid payment method in your Apple ID account,
for the first time you use the App Store, or iTunes, even if you only download free apps.
Apple support have articles online (links below) that may help.
First: Check the payment methods that can be used with an Apple ID:
Payment methods that you can use with your Apple ID - Apple Support
Says:
India
So it seems to me, that there may not not be any Bank Credit / Debit cards that Indian banks will allow. to be used for Apple.
If you have an Apple ID balance for Apple purchases:
What you can buy with your Apple Gift Card or Apple Account balance – Apple Support
NB: Some stores and apps might not be available in your country or region.
How to: Add money to your Apple Account balance – Apple Support
How to: Check your Apple Account balance - Apple Support
How apps, content and subscriptions from Apple are billed – Apple Support
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How to: Get apps in the App Store on iPhone – Apple Support
says:
The availability of the App Store and Apple Arcade varies by country or region.
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All the best :-)