When adding a user as an author in the "Allow specific people to edit this document" section of the Advanced Options in a document, a warning message appears with the text: "This user is not allowed to edit content in the selected space":
This article provides information about this issue.
Although this warning message appears, the user will be able to edit the document.
This issue has been identified as a defect. For more information, contact your account executive or customer success manager, referencing the code JVCLD-38506.