sign in to your Apple Account in the App Store
Sign in to your Apple Account in the App Store on your Mac to find, purchase, update, and download apps, or to manage your subscriptions.
If you don’t already have an Apple Account, you can create one on the Apple Account webpage.
Go to the App Store app on your iPhone.
Tap the My Account button in the top-right corner of the screen.
Tap Sign In with Apple Account, then tap Continue (sign in again if necessary).