Document Attachments allow you to attach downloadable files to your document. This is helpful for appending supplemental attachments, larger file types, Excel spreadsheets, and any other content you’d like to attach to — but not include in the body of — your document.
Please be informed that you can attach a file in document.draft
status only.
Limits
You can attach up to 10 files, and no file can exceed 50MB.
More details please find in the HelpCenter topic.
Attachments of the document bundling
Unfortunately, attachment creation is not allowed in document bundling.