Why is the appstore keep asking postal code here in Dubai, U.A.E. when it is not being used here, can't download anything from the appstore. The addres field is requiring something (postal code)not available in this place

Is Dubai your home, or are you just visiting? If you are visiting and you are trying to use the App Store in the AEU, but your iPad is registered in another country, you are tied to that iTunes store and this is why you would be experiencing issues in Dubai. If Dubai is your home, you need to set up your iTunes account for your country, and you need to have a credit card on file from the country you live.