Unable to access files in group
If you cannot access the files in a group (the PDF attachment is greyed out, or you receive the message "Unfortunately we do not have permission to make this file downloadable"), you are probably trying to access file attachments in a public group. You can only share file attachments in private groups. It is not possible to share files in public or public (invite-only) groups. If you wish to share files, you will need to create a new private group, and add the files there.