If you want to preflight PDF files in Switch using the PitStop Server Configurator, you must build a flow with the PitStop Server Configurator and set all properties correctly. As PitStop Server is an automated system, there is no manual intervention, so the values cannot be entered by the user. Instead, the values are taken from a Job Ticket - at least if the variable type is "Job Ticket". If this is not the case (i.e. if the variable type is "rule based" or "constant"), the default values are used. See also Smart Preflight Variables: types.
Note that all PDF files moved to the PitStop Server Configurator will be preflighted. No additional setup is required.
To learn more about the PitStop Server Configurator, search for the configurator in the Flow Elements pane and select Documentation from the context menu.