After the Mac boots, you are presented with this "Activate Mac" screen.
Click on the Wi-Fi symbol in the top right of the menu bar and select a Wi-Fi network you can connect to. Provide the password for the selected Wi-Fi network.
The Mac should activate within 1-2 minutes after being connected to the internet.
If the device was reset, the Mac will reboot after being activated and enter the setup assistant. The next steps are described here.
If the device was erased, the Mac will not reboot and instead offer to Exit to Recovery.
After entering Recovery, you can follow the next steps here.
What to do, if the Mac doesn't activate and asks for an Apple ID instead?
Apple devices are activation locked when the previous user enabled the "Find My" feature with a personal Apple ID. The "Find My" feature is a theft protection feature and gets enabled automatically, when signing in to a private Apple ID.
If the device was managed by WAY at the time the user enabled "Find My", WAY can provide an "MDM Bypass Code" which will allow you to disable the activation lock, please contact WAY support to receive it.
To prevent running into activation lock, users should use the "Erase all content and settings" feature on their device, it will always disable the activation lock.
If a user didn't remove the activation lock before the device was wiped, turn off the device so it is unreachable from the internet. Now you can ask the user to visit "Find My" on icloud.com/find. There, the user can remove the device from their Apple ID account, which disables the activation lock.
If the user can't be reached or is uncooperative, you will have to contact Apple's hotline and proof you are the legitimate owner of the device by providing the device's invoice.