Real-time co-authoring is a new feature of Microsoft Word 2016: https://support.office.com/en-us/article/Collaborate-on-Word-documents-with-real-time-co-authoring-7dd3040c-3f30-4fdd-bab0-8586492a1f1d
But on Microsoft Word 2016 for OSX I was not able to find how to enable it. I can share documents on one-drive with other people and see their modification. But I can't see their change in real-time (they have to save the document). This feature is missing on Mac?