Apps Installation

Is this a new account ? If you use these instructions when creating an account you should be able to : Create an iTunes Store, App Store, or iBooks Store account without a credit card or other payment method - Apple Support . If you didn't use those instructions payment details will need to be entered before anything can be downloaded, you should be able to remove the card after entering it

Are you currently in the country that you have as the country on the account ? Have you tried logging out and back into the account > Or put valid payment details on the account, you should be able to remove them after entering them

What message/prompt are you getting when trying to download apps ? Are you currently in the country that you have as the country on the account ?