Hi,
Here is process description:
you should have smart account (SA) and list of devices (virtual + hardware) in that smart account's PNP portal page (list can be added either manually or automatically if devices ordered with proper SA) . You should create vBond controller profile in PNP portal and assign devices to it (manually). Then download file and upload to vmanage (the second option to do that is sync between vmanage and smart account, then vmanage gets serial list).
https://www.cisco.com/c/dam/en_us/services/downloads/SD-WAN_pnp_support_guide.pdf
When overlay elements is deployed, vmanage pushes serial list to actual vbond controller. After that, if any router (edge device) tries to connect to vbond it gets authorized. Edge routers know about vbond through its local initial (bootstrap) configuration. Router connects to vBond either directly (when exactly vbond defined in config) or through PNP porta (so called ZTP/PNP process).
https://www.cisco.com/c/dam/en/us/td/docs/solutions/CVD/SDWAN/sdwan-wan-edge-onboarding-deploy-guide-2020nov.pdf
https://www.cisco.com/c/en/us/solutions/collateral/enterprise-networks/sd-wan/guide-c07-742221.html
HTH,
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