Server '{0}' is set up for a hybrid relationship with Office 365, but security isn't turned on for the Exchange Web Services ...

Server '{0}' is set up for a hybrid relationship with Office 365, but security isn't turned on for the Exchange Web Services (EWS) virtual directory '{1}'. We recommend that you turn on security for this EWS virtual directory. Click on the link 'get help fixing this issue' in the actions pane located on the right side of the screen for assistance.