Open the bindings panel.
Digital File pro will create a new binding group for each File Upload named "WA Uploaded File (<File Field Name>)" (where <File Field Name> is the name of the file field for the upload). IN that binding group is a binding for Server File Name.
You need to use the WA Uploaded (<File Field Name>) -> Server File Name binding in the insert record behavior in order to save the name of the uploaded file.