Hello Afif,
Please check if your institution is listed to avail this offer. In order to do that, when activating Azure for students there's a step where you have to perform academic verification, this will allow Microsoft to check if your institute is listed in database. Once that is verified you will be sent with an verification link to your education mail address.
If all of the above is indeed correct, I suggest you contact the Microsoft Azure Sales over here:
I would recommend going to the Azure for Education Contact page for support: or Azure Subscription Billing Team
Billing and Subscription team would be the best to provide more insight and guidance on this scenario, It's a Free support
Regards
Divya