The average number of views created by users per month For an admin dashboard aimed at tracking user engagement on Tableau Server, including the metric of the average number of views created by users per month is vital. This metric offers a clear insight into how actively users are interacting with and utilizing the server, thereby indicating the level of engagement and adoption. Option A is incorrect because disk space usage, while important, does not directly measure user engagement. Option C is incorrect as uptime and downtime statistics, while crucial for overall server health, do not directly indicate user engagement. Option D is incorrect because the total number of active users provides a static measure and does not reflect the dynamic nature of user engagement over time.