Thanks for reaching out for help in Apple Support Communities. I can see from your post that you're unable to download an app because it gives you an error message for credit card information. I also see that you mentioned you don't have credit card so I don't blame you for reaching out for help with this. If you're unable to choose none, it most cases this means you have an unpaid balance, or subscription that automatically renews. You can learn how to resolve this with the information in the link below.
If you can‘t choose None when you edit your Apple ID payment information
Hope this helps.