FileZila is the most prominent FLOSS (free / libre open source software) FTP server application in use in the litigation world and beyond. Just this past week when I had to get some deposition videos from a reporter, they took it for granted that I was familiar with it and would have it installed on my PC, as indeed I did. It can be downloaded here: https://filezilla-project.org/download.php?type=client . Keep in mind though that there have been reports that FileZilla upon installation will install malware, and alter your settings (such as your default search engine) without warning. You might want to consider having your office purchase proprietary software such as CrushFTP which has more features than Mozilla.
FileZilla is actually two programs - FileZilla Server - which you use to send files from your PC; and FileZilla Client which is used to download files from another PC. You may need assistance from your IT department to configure these correctly.