payamprivate on "[Plugin: WP Fastest Cache] Forbiden to buy premium version"

Hi Dear
I want to buy premium version of this plugin for my site: http://7ganj.ir

But when i click on the download button to buy and activate it ,
i get this error in this link:
http://api.wpfastestcache.net/premium/newdownload/7ganj.ir/f141460ecb8c2a707746838286663781
with content of :
Forbidden

why its Forbidden ?? is it because of our domain name ?? .ir ??
can you fix it for us :) ?

thanks

https://wordpress.org/plugins/wp-fastest-cache/