[Smush Pro] Cannot add staging site to licenses

Hi,

I am trying to ad the URL above to my accounts website as per here…
https://premium.wpmudev.org/hub/my-websites/
and am getting the error message “The site you chose doesn’t look like a WordPress site. Please try again”.

I have tried various variations o the URL but none seem to work.

Can you add the URL for me please OR tell me how to add it there?

Thanks
Tony