Notwithstanding its age, this format refuses to die. It is still popular where the help has to accessible offline and contained in a single file.
Click Output > Output Settings the first time you generate so that you can configure your preset as required. After the preset is configured, you can either come back here next time or you can click the Quick Generate icon top right in Adobe RoboHelp 2019.
The options are similar to previous versions and are described in detail in the online help.
The icons above the list of presets allow you to generate an output,
view it or create further outputs.