How can we get free app

If it's free, just go to the App Store on your phone and get it.

Shivamchy704 wrote:

I can login Apple account payment so I need free app

If you're trying to say that you do not have a payment method on file, my understanding is that you may need to have a payment method on file even to download "free" apps.

You won't be charged for downloading "free" apps, but many of them are like coin-operated vending machines, with functionality locked away behind "in-app purchases". The "in-app purchases" cost real money, and if you make any "in-app purchases", those will be charged to your payment method.