Filezilla is one of the best File Transfer Protocol (FTP) programs around and is so popular that many hosting sites give step by step instructions on how to use it to access them. There is also a site manager so it is easy to setup and save multiple servers for quick access.
To install Filezilla on Kubuntu 20.04 open up Konsole and type,
sudo apt install filezilla
After installation it can be found in the Applications Menu under Applications/Internet or by selecting the Applications Menu and typing its name.