I want Fampay app in my iPhone

It is in the App Store on your phone:

Read this document to learn how to download apps and games on your iPhone or iPad

Download apps and games on your iPhone or iPad - Apple Support

How to get apps for iPhone or iPad

1. On your iPhone or iPad, open the App Store app.

2. Browse through the Today, Games, Apps, or Arcade tabs to find apps you like. Or tap the Search tab to look for something specific. If you find a game that says Arcade, subscribe to Apple Arcade [at: Join Apple Arcade - Apple Support ] to play the game.

3. Tap or click the price or Get button. If you see the Open button instead of a price or Get button, you already bought or downloaded that app.*

In the App Store, if an app has a Get button instead of a price, the app is free. You won't be charged for downloading a free app. Some free apps offer in-app purchases and subscriptions that you can buy. Subscriptions and in-app purchases give you access to more features, content, and more.

* https://discussions.apple.com/thread/254977555?answerId=259261056022#259261056022

You need to double-click the physical button on the side of your iPhone to confirm the purchase - not the screen.