Microsoft.SharePoint.Client.Online.CSOM 15.0.4919.1000

This package contains the SharePoint Client Side Object Model libraries for 2013 (on-premises)

No packages depend on Microsoft.SharePoint.Client.Online.CSOM.

Be aware that the version of the client matches the version you have installed on the server. I got some messages that this version is newer than some people have installed on their server. So use the previous version, or make sure you have the latest patches installed on your server.