why cant i select none for payment information??

If you can‘t choose None when you edit your Apple ID payment information - https://support.apple.com/HT203905 - also make sure you don't have any active subscriptions or are set as the Family Organizer for a Family Sharing plan.

Related:

If your payment method is declined, or you have a billing issue with a previous purchase in the iTunes Store - https://support.apple.com/HT203005 - various reasons why payment method is declined.

If you have a pending payment you cannot download anything until you have resolved the situation by making the payment.

I've seen posts from others in a similar situation and they had to resort to:

iTunes [Store] Support - Use this form for assistance with account and billing, code redemption, or purchase questions - https://ssl.apple.com/emea/support/itunes/contact.html

You can buy iTunes/App Store gift cards in local stores for as little as $10. Redeeming that card and leaving the $10 credit on your account will allow you to download all the free apps that you want.

It's that or a credit card from a bank in your country of legal residence with a verifiable billing address in the same country.

ASC - Late 2012 Mac mini, macOS 10.13.3;  Watch, 38 mm AL, watchOS 4.2.2; iPad Air 2 & iPhone 7+, iOS 11.2.5; TV 4th Gen, tvOS 10.2.6;  Airport Express

If you can't select none, the other way is to buy an iTunes gift card and redeem to your account.

Free app is still free.