Case Community URL

We use the SF connector for Case management. Does anyone know how this field gets populated in Case: LiSFIntegration__Community_URL__c

We're struggling with customers who have tens and even hundreds of open cases and not having Case Search functionality is making it difficult for them to track status.

As a workaround we're planning to send them a report with open cases and we've just added a formulated field to take them to the Case URL when we noticed this field in Case but it's blank.