You must be an Administrator on your Mac to enable SharePoint Online sync.
If you're using the OneDrive Mac Store app, uninstall it.
Install the latest build of OneDrive for Mac.
Exit the new OneDrive sync client by clicking on the OneDrive cloud icon in the Menu bar and selecting Quit OneDrive.
Open a terminal window and run the following commands:
Defaults write com.microsoft.OneDrive TeamSiteSyncPreview -bool True Defaults write com.microsoft.OneDriveUpdate Tier Team Killall cfprefsd
Restart the sync client and log in again if prompted