My Nexus 5 phone running marshmallow can not sync calendar events with Outlook - Any suggestions?

Since receiving a new Nexus 5 about 3 months ago I have been unable to get the calendar syncing function with MS Outlook to work. I think it's a software patch issue but I am not technical and I can't believe that my IT guys can't make this work. Is this an unsolvable problem? If not can you give me a hint how to make the calendar sync happen?