The Hammerhead Karoo and Karoo 2 are standalone GPS units that are configured by a companion website through the Hammerhead dashboard portal. There is not a direct file sync service to this device, as you must use the Hammerhead website or extension to transfer routes to this device.
You can sync your Routes to Karoo using their custom website based route importer: https://dashboard.hammerhead.io/auth/signup
You can also use the Hammerhead Chrome Extension for easier access.
For more on this check out the Karoo/2 Support Document from Hammerhead with more info