Having trouble installing the Rock addon.

Just purchased the Rock Pianos Addon and am struggling with the installation.

My music computer does not have the internet.

So far, I have registered the rock addon in the user area.

I have been on the music computer and in Pteq have gone to update license - manual activation - and this has given me the long URL address.

After copying and pasting the URL it into my web browser on my laptop I receive the message: 

"You are trying to activate an add-on. To use the Rock Collection, you must register it in you user area: https://www.pianoteq.com/user_area, and update your licence in Pianoteq."

Not sure how to proceed, because in my User Area it says that the addon is registered (however, it does not have the manage button next to it as with the main Pteq software).

Any help appreciated