This feature facilitates the bulk upload of files or attachments, allowing them to be linked to multiple records. Users must create a CSV mapping file that includes record IDs and file/attachment names, which must be uploaded along with the files or attachments.
If you would like to learn more about this feature, please visit the following link: Mass File Upload: Additional Feature - Records CSV
Demo Video: https://www.youtube.com/watch?v=nzqA3c7ROho&list=PLXqeMW5vDpMA_VqPcBieEV7ZvDgkVYVGv&index=4
PS: View Mass File Upload, Salesforce file upload app on Salesforce AppExchange: https://appexchange.salesforce.com/appxListingDetail?listingId=82cf236b-1ee8-4ea7-aebf-fd0c89fb93bd