Required Files
Currently, to run the Porta SFTP Server on Linux (Ubuntu 20.04+), you only need to have the following files. Note that the files from your Windows installation (if you have one) can be reused(Copied over) to Ubuntu directly except the ones with the “.exe” extension.

Installing Java OpenJDK 17
sudo apt install openjdk-17-jdk openjdk-17-jre
Then verify using “java -version” command

File Permission
Right click the jar file ->Permissions tab and tick/check the “Allow executing file as program”

Running With Java Runtime
Right one more time and Open/Run the jar file with the OpenJDK Java 17 Runtime

Note. If you want to enable Fail2Ban firewall, please read this blog post.
Reference: How to Install Java 17 LTS on Ubuntu 20.04 – RoseHosting