The "Run script" task is part of the Automation Engine base.
Via the Preflight with Pitstop ticket in Automation Engine:
Via the Pitstop Profile Editor you can create an Action list, which changes the document information like adding an author, adding keywords, etc...
You can find the action in the Pitstop Profile Editor > Add Keywords > Standard > Metadata > Change document info.
After you apply the action by using the Preflight with Pitstop ticket, the metadata of the PDF will be updated:
The Preflight with Pitstop task is part of the Processor Module.