You should be able to use the garmin Mapinstaller to install the maps onto the card if they are unlocked; this seems to the be the case for most newer maps. Otherwise youll have to use mapsource to accomplish the install.
What file type do you have is it a map installer or a .img format?
I dont know if its still relevant but if its .img file there is still a way to break it down into a mapsource format using gmaptool if i remember correctly.
All the tools you would need should be posted in
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