Assume that you have installed KB 4015893, but have not run the Set-CsPlatformServiceSettings cmdlet to set the EnableDelegateManagement attribute to true. In this situation, installing this update will automatically set the value to true. This means that you enable the delegate management feature.
How to get this update
To get this update, install the December 2017 cumulative update 6.0.9319.510 for Skype for Business Server 2015, core components.