app store

You usually need to have added a valid payment method to your account. Even to re-download or update apps and for free apps. You can find the acceptable payment methods for your country here;

Payment methods that you can use with your Apple ID - Apple Support

M1 Mac mini, macOS 13.2.1; Watch, series 7 GPS/cellular, watchOS 9.3.1; iPad Pro 2nd Gen, iPadOS 16.3.1; iPhone 12 Pro, iOS 16.3.1; TV 4th Gen, tvOS 16.3.2; HomePods, audioOS 16.3.3 and Airport Express w/ Airplay 2

I only have completely free apps. I know I personally can download and update these apps without having a payment method, or even any account balance. However, Apple has various criteria for determining if you must have a payment method present. You are apparently encountering one of those. The payment method may not be charged if you also have account balance, but the payment method has to be present. Since it appears you are encountering one of those situations, you have no option but to enter a valid payment method if you wish to continue downloading. Read the support article Add a payment method to your Apple ID - Apple Support about how to do that. This next article lists valid payment methods for different countries but note that in this case Apple Account balance alone apparently does not meet the requirement: Payment methods that you can use with your Apple ID - Apple Support .