Downloading to Garmin 810

I have been trying to download some maps of Eastern France. I have selected Routable Bicycle.
When the link appears in my email, to which I then go, a zip file appears in my Applications support folder. There doesn’t appear to be any application that will open the zip folder so I have just tried to copy it over to the Garmin unit’s New Files folder. Nothing appears when I then go to Basecamp, the default program for Mac Mapping. I then tried to copy it to the The Garmin unit Courses folder but it then says there is not enough space!!
Can anyone perhaps explain what I may be doing wrong.

Many thanks

DCRainmaker may be able to help here, scroll down to the section headed “Openstreet Maps”
(There is a link to that section at the left of the page too)
I suspect that you will need to buy a MicroSD card to give you enough space to put the maps.
This site lists providers of Garmin suitable maps.
I have found the site a reliable site to get cycle suitable maps.