Your mac should also be using Mac OS X 10.12 (Sierra) or later. Office 2011 does not have the OneDrive App and was not built to use OneDrive or SharePoint (even though you may have limited success using)

However, to access SharePoint files you only need the “ OneDrive App” (available to all Office 365 Personal, Office 365 Home or higher. To setup SharePoint initially, you need at lease one licence of Microsoft Office 365 (Business, Business Essentials, Business Premium, Enterprise E1, E3, E5, SharePoint Plan 1 and 2) SharePoint is basically the Business version of OneDrive but your computer (Windows or Mac) uses the “ OneDrive-App” as the program that syncs files between your computer and the Microsoft Cloud. There is no such thing as a “ SharePoint-App“. SharePoint (OneDrive) stops syncing on older Macs from 10 Sept 21 If you or your company uses Microsoft OneDrive or Microsoft SharePoint for cloud data storage in a Windows PC environment as part of Office 365, it can also be setup to work the same way and access and edit files on a Mac OS device such as an iMac, Mac Mini or Macbook as follows. We show you how to install Microsoft’s OneDrive and Sharepoint on a Mac, so you can share files with other Mac and Windows users

Onedrive for business mac client