Add value to select list in Jira cloud using python and API

I'm trying to add new values to a multiple select custom field. I'm getting 401 response. The code taken from Atlassian documentation . Anyone knows why? maybe it is something with the authentication method?

import requests
from requests.auth import HTTPBasicAuth
import json

customers_id = "10163"
contextId = "int64"

url =   "https://MY_DOMAIN.atlassian.net/rest/api/3/field/{customers_id}/context/{contextId}/option"

auth = HTTPBasicAuth("MY_EMAIL", "MY_API_TOKEN")

headers = {
   "Accept": "application/json",
   "Content-Type": "application/json"
}
payload = json.dumps( {
  "options": [
    {
      "disabled": "false",
      "value": "Manhattan"
    },
    {
      "disabled": "false",
      "value": "The Electric City"
    }
  ]
} )

response = requests.request(
   "POST",
   url,
   data=payload,
   headers=headers,
   auth=auth
)

print(json.dumps(json.loads(response.text), sort_keys=True, indent=4, separators=(",",": ")))

You have "int64" which is a string, it should be 12345 or whatever your contextID is.

There might be something else going on here also: 401 is Returned if the authentication credentials are incorrect or missing. Is this your own Jira Cloud instance or one managed by someone else as you need the following permissions - Permissions required: Administer Jira global permission. So you may not have sufficient rights to make this call?