Curl JSON Get Request & Response Help

I think this module is exactly what I'm looking for, however I can't find the relevant documentation in order to successfully use it :).

I'm trying to create REST API call rules to connect with Citrix GoToTraining, however I first need to authenticate in order to even start making calls. I'm sadly stumbling already just with the authentication portion.

This is the example from Citrix as seen here: https://developer.citrixonline.com/page/direct-login

Example
Following is an example request and response using Curl:

$ curl -X GET -H "Content-type: application/json" -H "Accept: application/json"
"https://api.citrixonline.com/oauth/access_token?grant_type=password&user_id=test@test.com&password=xyz&client_id=123"

{
  "access_token":"3645136ef45675a113adb18027dd7df8",
  "expires_in":"30758399",
  "refresh_token":"1dd48bf4aa453162521250d772a03ae6",
  "organizer_key":"300000000000384444",
  "account_key":"300000000000329487",
  "account_type":"corporate",
  "firstName":"Test",
  "lastName":"Test",
  "email":"test@test.com"
}

Normally you would save the access_token and organizer_key values for subsequent API calls. Here’s an example using both of those to call Get Organizer:

$ curl -X GET -H "Content-type: application/json" -H "Accept: application/json"
-H "Authorization: OAuth oauth_token=3645136ef45675a113adb18027dd7df8"
"https://api.citrixonline.com/G2M/rest/organizers/300000000000384444"

[
  {
    "organizerkey":300000000000384444,
    "email":"test@test.com",
    "firstName":"Test",
    "lastName":"Test",
    "groupId":300000000000043430,
    "groupName":"Test",
    "status":"active",
    "maxNumAttendeesAllowed":25
  }
]

Any help would be greatly appreciated. Or any links that would help me further. Thank you.