On Pro and Business plans, Admins can control who can access documents in the workspace with user-specific permission settings to make private, view, edit, or share to everyone in your workspace.
The only documents any user can see are their own, unless they choose to share it with other users. If a user shares a document with another user within their workspace, it will appear in the receiver's email inbox.
Note: If you run into an issue, make sure that your browser does not have any pop-up blockers that will inhibit you from being able to sign up. Go ahead and turn those off, temporarily.