You can attach documents that already exist in OnBase to the form if the form you are using is configured to allow existing documents to be attached.
Note:
Attaching documents from OnBase is not available to users who do not have document retrieval rights.Users accessing forms through shared forms, DocPop, or FormPop also cannot attach documents from OnBase.
To attach a document from OnBase:
When the form is submitted, the documents are attached to the form.