Downloading with out a credit card

You can try this:

Create or use your Apple ID without a payment method - https://support.apple.com/HT204034 - "When you use your Apple ID to sign in to the iTunes Store, App Store, or iBooks Store for the first time, you're asked to enter a payment method so that you can purchase items from the store. Follow these steps if you don't want to associate a payment method with your account."

but if it insists upon a payment:

"Learn why you can't use your Apple ID without a payment method in the App Store, iTunes Store, and more." - https://support.apple.com/HT203905 - also make sure you don't have any active subscriptions, are set as the Family Organizer for a Family Sharing plan, or owe any money for past purchases.