Are there any security features to stop other drivers from using the charging unit?
From our experience this is a highly unlikely scenario, especially as your charging unit will have JustPark branding.
If you are a Fleet Driver with your own charger installed at your home, you can use the Wallbox device to lock your charger. More information on this can be found in the user guide.
If you are hosting a Fleet Driver, your driver will be able to lock the charger when they are not using it.