The Release Notes tab is a running list of updates and bugs for each ZPortals release:

The Activity History tab can provide an admin with details of changes that portal users make.

Note this might be relevant because in the system admin that connected ZPortals and Zoho CRM will always show as having made updates, additions, deletions in the portal due to the API integration. To enable history tracking, click into the History Settings sub tab and select "Activity Tracking" and then the app you would like to track:

The Error Log can be useful when users run into issues, specifically API related errors from Zoho or when a user attempts to sign in but cannot due to an incorrect password. It can also be helpful when a Zoho app is disconnected from the plugin and the authentication failure message appears: