First, you are using the wrong object when you use TreeManager. That object navigates the Test Plan tree. The objects returned by that NodeByPath method are Test Plan Tree SubjectNodes. And TestFactory can't be instantiated from a SubjectNode.
Instead you need to be using the TestSetTreeManager object and its NodeByPath method.
Second, based on what you included above for your path ("Subject\...\...\") you specified a folder path in the Test Plan module. You need to specify a folder path in the Test Lab module ("Root\...\...\") that will lead you to a Test Lab folder containing test sets that contain the Test Case Instances for which you want to extract associated Run information.
Lastly, to create a filter, have you studied the OTA API documentation for the Filter object and looked at the examples? There are lots of examples of how to set filters for various objects. You should be able to extrapolate from the examples to design a filter for the Run information.