Cannot Turn On Features in Configuration Manager Current Branch
If this is your first time seeing a bunch of feature that are turned on or turned off in the Administration > Cloud Services > Updates and Servicing > Features node of the console and wondering why the option to Turn On a particular feature is greyed out. This is because it has to be turned on in the Hierarchy Settings.
The exact place to do it in the console is to browse to Overview > Site Configuration > Sites. Once there, click the Hierarchy Settings button at the ribbon.
At the General tab of the Hierarchy Settings, select the checkbox for Consent to use Pre-Release features, then click OK.
Back to the features node in the console and now, you have the option to Turn On a feature enabled.