Attachments are files stored in Google Drive, owned by the storage account of the library. Attachments are elements of an AODOcs document.
To download attachments from AODocs documents:
1. Open an AODocs document in any type of library.
2. Open the More actions menu next to the attachment and select Download Attachment.
2. If the file is a non-Google file, the file downloads to your computer immediately.
3. If the file is a Google file (Docs, Sheets, Slides), a pop-up opens. Select the format you want to download the file as. Press Close. The file downloads to your computer.