How to change region

If you can’t install apps from App Store even after signing in then you better speak to Apple Support and to change region go to settings>general>language and region and chose region you are located in. You might not be able to add a payment method because the card might or the payement method might not be available and compatible with Apple in your region

Hope this helps

The message that appears on-screen suggests that you have recently changed the region to which your device is registered. If this is the case, you’ll not be able able to change it again for 90 days. This lockout period is intended to prevent account abuse.

If you are certain that you have not recently attempted to change your account region, you will need to directly contact Apple Support for assistance. You will find the Contact Support link at top-right of this page.