If you are using Basecamp 4.7 (released in May 2018) then that is likely the problem. This version of MapInstall does not work with registry format maps, which is probably what you have. This has been a huge problem for everyone, but Garmin has discontinued Basecamp and will never fix it.
See this thread for some solutions, which include downgrading to an older version of Basecamp or using Mapsource, Garmin's old software.
https://forums.gpsfiledepot.com/index.php?topic=4539.0If you want to use Mapsource, there will be another issue on the DriveSmart however. Automotive devices are recognized as MTP devices and not USB disks on Windows computers. This means Mapsource will not "see" your GPS. But you can change this with a hidden menu on the Drivesmart - see this
http://forums.gpsreview.net/discussion/comment/165763/#Comment_1657632. Start NUVI by itself and go to Volume Screen.
3. Press the upper right hand corner of screen for 10 seconds.
4. The Developers Screen will pop up
5. Scroll down to MTP SETTINGS
6. Change from AUTO DETECT to MASS STORAGE