The current Collaboration update is part of an initial phase that expands collaboration capabilities within Atticus. At this stage, all participants, including beta readers and editors, need their own Atticus accounts to collaborate directly.
We completely understand the importance of being able to share your work with non-Atticus users and this functionality is absolutely part of our longer-term plans. However, implementing this feature requires building an additional layer of security and systems to ensure both the integrity of authors' work and safe interactions with non-Atticus users.
In the meantime, to collaborate with non-Atticus users, the options are to export your file to .docx, PDF, or ePub formats and share these documents for feedback outside of Atticus.