Under certain conditions you may opt to acquire a firewall manually rather than using Zero Touch.
To acquire a firewall manually:
1. Navigate to Manager View | Firewalls|Inventory.
2. Hover over the firewall, click the Ellipsis icon in the Action column and select Edit Settings. (If Zero Touch is enabled, settings will be greyed out)
3. Enter IP Address with Port for your device.
4. Enter Username and Password of the firewall.

5. Click Save and Acquire Again.
As part of the device acquisition process, NSM establishes connection to the device, configures the firewall to send out syslog heartbeats so its health can be monitored, and then pulls the status and configuration of the firewall. The status of the device acquisition is displayed in DEVICE ACQUISITION STATUS section; If the acquisition is successful, you will see a green icon next to Acquired. The firewall is now managed by NSM, and the CONFIGURATION is displayed as Managed in the Firewall Inventory page.
How to add a firewall to NSM using Zero Touch: https://www.sonicwall.com/support/video-tutorials/how-to-add-a-firewall-to-nsm-using-zt/6365966041112