Welcome to the forum newer devices like this one need their firmware patching to use Unlocked maps.
look in the garmindevice.xml & confirm your HWID is 2586 then go to the patching thread below.
<PartNumber>006-B2586-00</PartNumber>
<SoftwareVersion>670</SoftwareVersion>
<Description>Garmin DriveSmart 51</Description>