FROM OUTLOOK, right click Outlook icon in system tray holding down Ctrl key, and select "Test E-mail AutoConfiguration....". Only check Autodiscover.
THAT'S the way it works...........remember to set values matching the CN of certificate on Default Web Site.
Otherwise, you can create mutliple web sites each one with appropriate certificate. Example: mail.company.com, autodiscover.company.com, AND Leave the Default Web Site with Default Self Signed Certificate, so Outlook doesn't show cert warning.