If you just want the raw files downloaded you can just create a report that holds the URL to the file attachment field and use a
FREE browser extension such as
DownThemAll to do the bulk download.
DownThemAllhttps://www.downthemall.net/Oftentimes users want not just the raw file downloaded but some of the metadata associated with the record this file attachment is in. In this case you need to spec out your requirements and use some simple script to coordinate the downloaded files with the downloaded CSV or spreadsheet associated with the metadata