When you first click Add New Step, both the Action Link field and the Help Link field default to green Has Link notes.
To add a link to a document to a step, first copy the document URL (make sure the sharing is set so that anyone in your firm can see the document). Then click in either the Action Link field or the Help Link field and paste the URL.
When you click the Save Changes button, fields where you pasted a link will have a green Has Link note and fields with no link will have an orange No Link note.
When a user accepts an Aero that has steps with links, the link will show up as clickable blue arrows.