Automation Action Parameter as Dict


I am running into trouble trying to pass an event payload dictionary, from a webhook, to an automation action flow parameter.
I have a flow which takes in an input parameter of type dict (attachments):
(Screenshot 1)

This is then deployed as a deployment via prefect.yaml:
(Screenshot 2)

I then have an event webhook that takes in a payload in JSON format:
(Screenshot 3)

Then, in my automation trigger I am looking when this webhook was received:
(Screenshot 4)

In the automation action, I am selecting to run the deployment shown above, and in the input parameters I am trying to pass a JSON field called ‘attachments’. The keys in the ‘attachments’ JSON are random, so I can’t pass them directly. I’d like to pass the entire ‘attachments’ JSON into the input parameter in dict format. When I go to change the input from null to something like {{ event.payload.attachments}} using “Jinja Input” I get the following error:
(null - Screenshot 5)

(Jinja Input - Screenshot 6)

(Error message - Screenshot 7)

(Flow Run Parameters - Screenshot 8)

How can I pass the event payload as an actual python dictionary?