Purchased map download to computer

I have a Garmin Zumo 590 that I purchased in Australia that came with preloaded Australian maps. I have purchased the North America map( Twice) and have downloaded it successfully to my GPS but can't download the purchased map to my laptop. I have successfully downloaded the pre loaded Australian map to my laptop but have no success in doing the same with  purchased map.

Any advise or help will be greatly appreciated.

Jeffrey