It should show up as a drive. The fact that it does not is why GC cannot find it.
Are you on Windows or a Mac?
For Windows you could try loading the USB drivers. https://www8.garmin.com/support/download_details.jsp?id=591
Windows (10). All my (many) other Garmin devices are recognized by GE without a problem, but I'll reload the drivers just to make sure. Thanks.