The DEVICE | Settings > Storage page on the Template View allows you to enable the storage options for the System and Threat Logs as well as the Packet Capture Logs.
To enable storage settings
Click on the Storage tab under Settings.
Configure the following options under System and Threat Logs:
Enable the Enable Logging to Storage for storing system logs, threat logs, audit logs, and AppFlow report data to the External Storage.
Select Primary or Secondary from the Logs Storage Device Type drop-down.
Enable the Enable Logging to Storage option under Packets Capture Logs.
Click OK.
Enabling Enable Logging to Storage requires a reboot for the changes to take effect.