Appain Oauth 2.0 Clients Web API Configuration Not Working

I am attempting to set up an Oauth2.0 client credentials grant authentication for our application web APIs. I believe I have done the configuration correctly but I'm clearly missing something because when I attempt to get an authorization token using postman I am a failed client authentication. Here is the sequence of configurations I have performed in order.

1. I created an Oauth2.0 Client in the Admin console creating a new service account in the process.

2. I copied the client_id, client_secret, and access token url.

3. I created a Web API object. For connectivity testing I'm just using the GET Hello World configuration. I added a path value to the web api and copies the URL.

4. I then added the service account to the admin group which secured the new Web API object.

5. In postman I created a new request. I gave it the copied url.

6. Under authorization I selected Oauth2.0 and under configure new token I included the grant_type, client_id, and client_secret (see below image.)

When I hit the get new access token button I get a failed message.

And of course if I simply try to run the request I get a bad request error. I'm pretty familiar with API requests at this point but Oauth2.0 authentication is clearly new to me. If anybody can see where I went wrong I'd really appreciate the insight.