Nothing technically gets transferred to Meraki.
When you make a purchase and the reseller notes the DEP ID, it is Apple whom associates that device with your organization.
Apple maintains the DEP side of the house, and it is their servers who know iPad S/N:1234 belongs to XYZ Corp.
When you link your Meraki EMM account with Apple's DEP, Apple then knows when the iPad is being turned on and registered, that it belongs to XYZ Corp based on it's serial number and forces the device to have the associated Meraki profile installed.
The big benefit to DEP, is that if someone was able to wipe one of your iPads, they'd never technically be able to unassociate it with your DEP, and it would always end up being force enrolled back to your company.
https://images.apple.com/business/docs/DEP_Guide.pdf