I downloaded the City_Navigator_Southern_Africa_NT_2021_20.gmap from this site, within the Maps folder on basecamp I can use it on the desktop, I need to transfer this mapset to the etrex20 without using an additional sd card.
Using the mapinstall function it shows - No unlocked maps were found for this device.
I also copied the .gmap file to the root directory of the device but still I dont see the mapset
Any guidelines?