How much of a review will the manuscript author see?
The only part of a review an author will ever see are the sections of the review that have been configured as "visible to author". Editors can also share reviewer file attachments with the author when issuing a decision. Overview questions (Overall Rating, Comments to editor, and the publication recommendation) are always visible only to editors.
The journal admin user can customize which questions on the reviewer feedback form are visible to the author by navigating to My Journals > Peer Review > Peer Review Settings > Reviewer Settings > Customize Reviewer Form, then editing any of the questions (aside from the Overview questions which cannot be edited), toggling the visibility, then saving the changes to the journal.
To learn how to disable any progress notifications for authors besides decisions, check out this walkthrough.
To learn more about being an editor, check out our Editor Guide.