After updating the firmware to version 7.09 here is how to obtain map:
go to Garmin crystler page.
https://auto-update.garmin.com/auto-update/site;jsessionid=E084E27D3B866779EAC2903EAF01109F
Select 2015 dodge challenger ~$180.
Purchase map, receive USB update in mail. Follow prompts to verify serial ID, and download two files (all explained in instructions). Remove USB from your computer, Go to Car. Enter dealer mode here
Select "back"
Insert your USB without navigating to any screens. New Map will automatically be detected and downloaded. Map download will take 1.5 hours so engine must remain on.
This took me 3 weeks to figure out (dealership didn't know how to update maps, even if I did want to pay the $1,100 for the map update, which I would never do.