An error occurred while saving the commentJoe Wilcoxson commented
This is a pretty big issue in the current version of Office365 for Mac. On Windows, you can directly open a Word/Excel file that is stored in OneDrive or Sharepoint and it automatically recognizes it as such and enables Autosave and Co-authoring. On the Mac, it is opened as a local file, without the additional features. The only way to use Autosave /Co-authoring on the Mac is to open the file from "Online Locations" within Word/Excel or by going to the OneDrive website and opening the file from there.