This update let you enable the delegate management feature for Unified Communications Web API (UCWA) that’s based on Microsoft Skype for Business Server 2015.
How to get this update
To get this update, install the May 2017 cumulative update 6.0.9319.281 for Skype for Business Server 2015, core components.
Note After you install this update, run the following Skype for Business management PowerShell command to enable the feature:
'Set-CsPlatformServiceSettings –EnableDelegateManagement $true'