my friend give me a whatsapp app as a gift in australia but i cant install on my iphone 4s please tell me a solution

My friend send me a app as a gift but i can't install on my iphone 4s please tell me the solution.

App Name WHATSAPP

Sender Destination Australia(Sydney)

The Problem is i open the app and he says reedem the code i reedem the code but he tell THIS CODE IS VALID FOR CUSTOMERS OF THE AUSTRALIA STORE please tell me the solution my friend buy this app please tell.....

Thanking you

Your IPHONE Customer

Amit Sharma

India

<Email Edited by Host>