A drip campaign is a pre-built series of emails or texts that a CRM sends a lead automatically over days or weeks. It is a nurturing tool, and it lives in your CRM, not in an open house sign-in app.
This is a useful boundary to understand. An open house app captures and qualifies visitors at the door and hands them to your CRM. The CRM then runs the drip. OpenHouse is not a CRM and does not run drip campaigns; it sends the first touch and passes the lead on.