Newbie help

I’ll be traveling to Germany soon and want to use my old Garmin Nuvi 2595 for in-car navigation instead of paying extra for a rental car with this feature. Only map currently loaded is North America. After reading several pages about this, it seemed pretty straight forward at first. I’ve downloaded the Germany OSM zipfile from http://garmin.openstreetmap.nl/ to a formatted a microSD card, then transferred gmappsupp.img into a folder named GARMIN to the card. When inserting the card into the unit, it doesn’t do anything. There’s no other option other than North America in myMaps. Is there something I’m missing?

I’ve tried putting both the zip file and .img on the card, tried both Generic Routable styles (old and new), and tried to plug into my Mac via USB with no luck (does not recognize unit).

Sorry for such a basic question but was really hoping this would work rather than buying the Euro package for this old unit. Any ideas. Thanks!

There are a few options why it does not work:
On some nuvis the default map folder is not called “garmin” but “map”
Maybe the micro sd card is not supported because too big (>32gb) or not in the right format (Fat32)?

See also https://help.openstreetmap.org/questions/4810/what-should-i-do-with-a-gmapsuppimg-that-i-downloaded