Custom Object Record Bulk Jobs API returning 403 for trial account

Hi, I am using a Zendesk trial account and getting a 403 response for the API below.  All other APIs are working fine with the same credentials. I have ensured that I am doing a POST request and using the correct API URL with https. 
What might be the problem?

API that is not working - POST /api/v2/custom_objects/{custom_object_key}/jobs

APIs that are working with the same credentials:
Create Custom Object Record POST /api/v2/custom_objects/{custom_object_key}/records

List Custom Objects GET /api/v2/custom_objects

I referred to this article: https://developer.zendesk.com/api-reference/custom-data/custom-objects/custom_object_records/#custom-object-record-bulk-jobs 

I am using the code below to execute the API (sensitive fields masked):

url = "https://<account_id>.zendesk.com/api/v2/custom_objects/cars/jobs"
payload = json.loads("""{
    "job":
    {
        "action": "create",
        "items":
        [
            {
                "custom_object_fields":{
                    "color": "Red",
                    "year": 2020
                },
                "name": "2020 Tesla"
            }
        ]
    }
}""")
headers = {
    "Content-Type": "application/json",
}

email_address = '<email>'
api_token = '<token>' 
# Use basic authentication
auth = HTTPBasicAuth(f'{email_address}/token', api_token)

response = requests.request("POST", url, auth=auth, headers=headers, json=payload)
print(response.text)