HubSpot Custom App - Connection to Scenario

I’m stumped. And getting depressed.

Does anyone have experience connecting a HubSpot Timeline Events function to a scenario?

Background: I actually did this once. I made a custom app in my HubSpot developer account. I installed it on a client HubSpot account. I used Integromat to pass answers from a typeform into the timeline for contacts after they complete the form.

I don’t recall the exact process for initiating a connection for the app from inside the scenario, but I don’t remember it being difficult.

Now, I’m trying to do the same thing again, but I’m really struggling with the connection because of a URI mismatch when the OAuth modal opens and tries to authorize the scope.

I don’t understand how the ‘create connection’ module inside the scenario is building the URL to ensure the URI redirect will match. It looks like I have no control over it.

Anyone here done this a couple times and can help me out?

Screen Shot 2022-03-23 at 5.25.05 PM