How can I download apps from the App Store when it's not available in my country?

That is the whole purpose of restricting apps by region so you will not be able to download it. The developer of the app chooses the regions where they want there apps to be available. Some regions, such as the EU, requires additional information from the developer and if the developer does not want to provide that information, you will not be able to download their app in that region.

You’ll need to be located in a country or region where Apple does business.

If the app is not available in your country, you cannot download it. There is no way around that.