Why am not able to download the app and update the apps

Change or remove your payment information from your iTunes Store account (Apple ID) - https://support.apple.com/HT201266 - "On your iPhone, iPad, or iPod touch, you can change the payment information for your Apple ID in Settings. On your Mac or PC, you can change your payment information from the iTunes Store." - More information at: https://discussions.apple.com/thread/3251676?answerId=15891166022#15891166022 and another tip at https://discussions.apple.com/thread/8010960?answerId=32902784022#32902784022

Payment methods you can use in the iTunes Store, App Store, and iBooks Store - https://support.apple.com/HT202631 - debit cards are not accepted in all countries and even if they are accepted they may not be accepted for all types of purchases.

Until your billing info is correct, you will not be able to update/download any apps.

Tips: Use a valid credit card with your name and is issued by your bank.