FileZilla is an open source file transfer solution that supports FTP, FTPS and SFTP. This application was selected for the European Union bug bounty program among many other applications.
The developers of the application have been released and FileZilla Pro, a commercial version with features that add support for WebDAV and many file storage services such as Google Drive, Box, Dropbox, Microsoft OneDrive, Digital Ocean, Amazon and many more.
The main download page offers the application only for Windows, but this particular version also includes adware. The download page emphasizes this: “This installer may include grouped offers. Check below for more options.
If you download the application from this page you may have a Windows Defender alert for potentially unwanted software.
The "App: FileZilla_BundleInstaller" threat appears when the file is scanned by Defender.
Of course it will not be possible to run the installer until the file is allowed to run by a system administrator.
However, there is a better option as the project keeps copies of the adware-free version of the program. All you have to do is visit the URL: https://filezilla-project.org/download.php?show_all=1
This download page lists all downloads for Windows, Mac OS and Linux without adware.