In v71+ of CloudReady, a new Settings menu item for "Connected Devices" showed up in CloudReady and Chrome OS.
On CloudReady, this setting does not work and errantly shows that the setting is "enforced by your administrator" even on personal accounts and unmanaged Chromebooks.
On Chrome OS, this setting is meant to enable integration with an Android phone for messages, proximity unlocking, and tethering.
You can still use message integration by visiting messages.android.com and following the instructions there.
The other functionality is currently not available on any Edition of CloudReady. We don't have any information at this time on whether it will be enabled in the future, but our release notes will include any updates.