If a coauthor you want to work with is not on Authorea, when you click Share or Manage Collaborators, you have a chance to enter their email address. They will receive a notification to complete sign up and immediately collaborate with you on the document.
You can also add a coauthor to the author list without inviting them to Authorea (they will not receive an email); to do so, simply type their name in the input box and add them as "a name".
To show someone your work and receive comments (even if the article is not public or published), access your document in Edit mode and you can click Share and then create a shareable URL, i.e. a secret link which you can share with your colleague.
Published on: 12 / 13 / 2017