Obtener datos de usuario desde una lista de Mailchimp

Esta consulta obtiene los datos de los miembros de una lista de Mailchimp.

query FetchUserDataFromMailchimpList(
  # mailchimpDataCenterCode: Code for the data center of your account on Mailchimp (See: https://mailchimp.com/developer/marketing/docs/fundamentals/#api-structure)
  $mailchimpDataCenterCode: String!
  # Audience ID for the list on Mailchimp to which to subscribe the email
  $mailchimpAudienceID: String!
) {
  mailchimpUsername: _env(name: "MAILCHIMP_API_CREDENTIALS_USERNAME")
    @remove
  mailchimpPassword: _env(name: "MAILCHIMP_API_CREDENTIALS_PASSWORD")
    @remove
 
  mailchimpAPIEndpoint: _sprintf(
    string: "https://%s.api.mailchimp.com/3.0/lists/%s/members",
    values: [$mailchimpDataCenterCode, $mailchimpAudienceID]
  )
    @remove
  
  mailchimpListMembersJSONObject: _sendJSONObjectItemHTTPRequest(input: {
    url: $__mailchimpAPIEndpoint,
    method: GET,
    options: {
      auth: {
        username: $__mailchimpUsername,
        password: $__mailchimpPassword
      }
    }
  })
    @remove
  mailchimpUserData: _objectProperty(
    object: $__mailchimpListMembersJSONObject,
    by: { key: "members"}
  )
}

Y define en wp-config.php:

define( 'MAILCHIMP_API_CREDENTIALS_USERNAME', '{ username }' );
define( 'MAILCHIMP_API_CREDENTIALS_PASSWORD', '{ password }' );