Hello O H,
Thank you for reaching out to NVIDIA Networking community. A switch operating system is required in order to connect devices over the network. When purchasing a switch loaded with Cumulus or OYNX (ethernet network operating system) you will be able to connect devices out of the box.
When purchasing a switch with just ONIE installed you would have to install a open source networking operating system (NOS) such as SONiC or upgrade to ONYX/Cumulus NOS. A valid NOS is required for devices to communicate over the switch.
Licenses and software images can be downloaded with a valid support contract, further information about support contracts can be obtained at the NVIDIA Networking Store or your local re-seller where you purchased the switch.
Best,
Brian
NVIDIA Networking Technical Support