If you're unable to make a purchase, it may be due to various reasons. To resolve this issue, please try the following steps:
Check for any restrictions:
Go to Settings > General > Restrictions
Approve any necessary permissions
Update your payment information and log into iCloud.
Log out of App Store by following these steps:
Go to Settings > App Store > Apple ID > Sign Out
Restart your phone.
Log back into your App Store account.
Update your payment information:
Go to Settings.
From the App Store menu, tap your Apple ID (enter your password if prompted).
Select Payment Information.
Enter the ‘Required Security Code’ in the appropriate field.
Click ‘Done’.
If the problem persists, please reach us by the “Contact Us” section.