@koster Hmmmm, easiest way I can think of is sharing your documents not on this platform. So like in the form of Google docs or whatever you and the author prefers.
Thank you for your wonderful advice! I was wondering what happens if a beta reader wishes to be anonymous. Personally, I am interested in beta reading but don't wish my username to show up at co-author on the story. Do you have any advice?
The author can add you as a co-author. You should be able to edit the chapters then.
The co-author option can be found on the forward and description page of the story. If you scroll down to to the part where it says "Characters" you'll see a blue Link that says "Add Coauthors". Click on the link and the author should be able to type in your username and find it. Once that's done, save and close. Then you should see a request.