How do I set up PostMan for importing data via API?

I have created a WorkFlow API endpoint, and followed this guide for getting it set up with Zapier:

However there is a low limit on Zapier for the number of records that can be processed - so I am trying to set it up in postman to pass the request to the same end point.

I have PostMan set to POST with the URL being [link from settings page]/[endpoint name] just as I had set up in Zapier.

The body of my request is set to Raw, and I have tried both TEXT/JSON for the types. It is formatted as
{
“field 1” : “value”,
“field 2” : “value”,
etc.
}

I have tried with auth, no auth, text, json, etc. And every time I try to send the request, I get the following error:

<html>

<head>
	<title>400 Bad Request</title>
</head>

<body>
	<center>
		<h1>400 Bad Request</h1>
	</center>
	<hr>
	<center>cloudflare</center>
</body>

</html>

I feel like I am missing something very simple. Do I need to nest the body inside another tag? Is it a limitation of still being on the Hobby plan? I thought that might be the issue, but Zapier imported a handful of the records on it’s own just fine - but I have way more than their limit.

If you set the API Workflow’s parameters to “Detect” and do the Postman Post … it should read most things.

I tried that as well an am still getting the 400 error.