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

Server '{0}' is set up for a hybrid relationship with Office 365, but security isn't turned on for the Exchange Autodiscover virtual directory '{1}'. We recommend that you turn on security for this Autodiscover 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.