Accessing data in the automation run cache


I am wanting to use the automation feature to conditionally send a notification triggered by a segment event. I have the segment integration working. The trouble I am having is with passing data from the segment event to the fetch data step. I’ve tried doing it a few ways that I have seen in the docs but always get an invalid step error in the automation editor. I have included a screenshot of my most recent attempt. Please let me know if what I am doing is possible and what the correct doc is to look at; they all seem to be telling me slightly different things.

Thank you!