Making OAuth work with Infusionsoft Ruby Gem

We are building an integration with our application. After talking to support on the phone it was told to us that we need to use OAUTH to connect our integration to the API. We are using the following GEM: GitHub - nateleavitt/infusionsoft: Ruby Gem for the Infusionsoft API

We created an infusionsoft.rb initializer and did the following:

1: Created our authorization link and logged in to authorize our app.
2: Received our code in the URL to use in our next step which was creating an access_token which we did with postman.
3: After this was completed we set up our initializer to have the following settings:

Infusionsoft.configure do |config|
config.use_oauth = true
config.api_url = ‘’ # do not include https://
config.api_key = ‘ACCESS_TOKEN’ # access_token
config.api_logger =“#{Rails.root}/log/infusionsoft_api.log”) # optional logger file

We replaced ACCESS_TOKEN with what was returned to us in postman.

After executing the call to create a contact:

Infusionsoft.contact_add({:FirstName => ‘first_name’, :LastName => ‘last_name’, :Email => ‘’})

We received an Authentication Failure. Prior to any of this, we received an invalid token. There is nowhere in the interface that allows me to debug the issue other than the response is Authentication Failure.

What might we be missing? If there a different parameter that I need to be passing?