I can’t download any apps

That means that you must update your payment method. You must have a valid payment method in your account to download any apps, even updates and free apps.

If you don’t have any apps with in-app purchases and don’t have any subscriptions you may be able to delete all payment methods, but if there is a payment method it must be valid.

See→Change, add, or remove Apple ID payment methods - Apple Support

and also→If you can't remove your last payment method or use no payment method with your Apple ID - Apple Support