ZeeDrive offers two options for opening Microsoft Office documents; either in exclusive editing mode which is similar to the behaviour when working from a traditional on-premises file server, or, opening the document for co-authoring. When opened for co-authoring, advanced Office features such as collaborative editing and AutoSave are available.
When an Office document is opened for co-authoring, the AutoSave slider is set to the On position
When editing documents with co-authoring enabled, you can see the edits of other users live in your document: