formatting a Post Request

I am hoping someone can help me. I am trying to obtain an OAuth token via a post request to Wild Apricot. Looking at their documentation it says I need the below. But I can’t figure out how to get it all into the KNIME Post Request node so that it works. Can anyone help with how to set this up? I have my API key and I can encode it into base64 with no issue.

POST /auth/token HTTP/1.1

Host: oauth.wildapricot.org

Authorization: Basic BASE64ENCODED(“APIKEY:YOURAPI_KEY”)

Content-type: application/x-www-form-urlencoded

granttype=clientcredentials&scope=auto

Here is an example with a nonvalid API key

POST /auth/token HTTP/1.1

Host: oauth.wildapricot.org

Authorization: Basic QVBJS0VZOm85c2U4N3Jnb2l5c29lcjk4MDcwOS0=

Content-type: application/x-www-form-urlencoded

granttype=clientcredentials&scope=auto