For anyone who might decide to purchase a license for FileZilla Pro for Linux – Pop!_OS (Ubuntu) in my case – and you want to have an icon to open the application instead of using the command line, try the following:
Extract the files (assuming your bz2 file is in your Downloads folder)
$ cd Downloads
$ tar -xvJf FileZilla- (tab to autocomplete)
Move it to some place nice
$ sudo mv FileZilla3 /opt
Then create the .desktop file
$ vim ~/.local/share/applications/FileZilla.desktop
Paste the following text
[Desktop Entry]
Name=FileZilla Pro
GenericName=FTP client
GenericName[da]=FTP-klient
GenericName[de]=FTP-Client
GenericName[fr]=Client FTP
Comment=Download and upload files via FTP, FTPS and SFTP
Comment[da]=Download og upload filer via FTP, FTPS og SFTP
Comment[de]=Dateien über FTP, FTPS und SFTP übertragen
Comment[fr]=Transférer des fichiers via FTP, FTPS et SFTP
Exec=/opt/FileZilla3/bin/filezilla
Terminal=false
Icon=/opt/FileZilla3/share/icons/hicolor/scalable/apps/filezilla_pro.svg
Type=Application
Categories=Network;FileTransfer;
Version=1.0
StartupWMClass=Filezilla
Save your file and your done. Enjoy!