Activity Creator - Setting An Argument to pop the ArgumentCollectionEditor

I’ve setup a project for Custom Activity Creator (VS 2019 extension). The goal is to setup a library activity, where one of the properties is a set of parameters (see first screen shot). After looking through some forums, I found that the ArgumentCollectionEditor class had the code to trigger that UI, however, i can’t figure out how to connect the argument to that class, see screen shot 2). Any help would be greatly appreciated!

Desired Pop Up on a property (usually has an ellipsis and the work (Collection) filled in, but this is the form I want the consumers of my library be able to interact with:

Activity Creator - After
2020_07_23_ActivityCreator_ArgumentCollectionEditorScreenshot|690x336 !