When there are multiple parent records involved, the app renames the zip file to "{massfildownload-yyyymmddhhmmss}.zip". This format ensures that each download session has a unique identifier based on the date and time, preventing any naming conflicts.

PS: View Mass File Download, Salesforce file download app on Salesforce AppExchange: https://appexchange.salesforce.com/appxListingDetail?listingId=a0N3A00000EcsAOUAZ