Once you have the correct settings established, this is what you should see. With this old Garmin Edge 500 it takes 30 seconds for the drive to show in ES File Explorer. Also, you may need to uninstall file cleaning apps such as Power Clean and reinstall File Explorer for the app to work correctly.
OTG cable from Android device to mini-USB cable. This allows connection and transfer of files to/from Garmin Edge 500 with ES File Explorer app.