When you share a document in Lumin, you can choose what level of document permissions you want to grant your collaborator.
When you select the Share option and enter your collaborator's email address, you will be presented with a dropdown of sharing permissions.
Can View: Collaborator can view the document only
Can Comment: Collaborator can view the document as well as make comments
Can Edit: Collaborator can view the document as well as use the toolbar to make edits to the document
Can Share: Collaborator can view, make edits, and share with other collaborators
Note: You can also bulk update team member permissions, learn how here.