From the Workspace window, you can Control-click on any document and choose Copy Link to copy a link to the document in a Workspace to your clipboard.
How to share a link from the Mac app’s Workspace window
In an open document, click on the 
in the Collaboration menu in the toolbar and choose Copy Link to copy a link to the document in your Workspace to your clipboard.
How to share a link from the Collaboration menu in the Mac app’s toolbar
You can find both Copy Link and Manage Share Settings in the menu bar under File > Workspace as well.
Open a document, click the Document Details 
icon, then click Share in the panel. Alternatively, click the and select Share. From here, you can invite other people via email to edit or view your document — as well as defining what people with a link to your document can do.
How to share a document by email in the web app