You are not being charged to download free apps.
- You may need a valid payment method to download apps even if they are free, but you will not be charged to download free apps. Most of those apps contain in-app purchases that will charge that payment method if you choose to use one of those options.
- If you have a previous purchase that was not able to be processed, then you will be required to pay any amount you owe from a previous purchase before you are allowed to use the App Store to download any other app.