Yubikey Import into Auth0

I’m trying to use a python code below, generated by ChatGPT to import five “yubikey 4” tokens to a free subscription. I’m not assigning the tokens to users at this time, I’m rather intend to just add it to the tenant. I have a CSV with “secret” and “serial” columns.

import csv
import json
import requests

AUTH0_DOMAIN = 'dev-xxxxx.us.auth0.com'
STORAGE_KEY = 'yubikeys'  # This key is used to store YubiKey data in Auth0 metadata

def load_yubikeys_from_csv(file_path):
    yubikeys = []
    with open(file_path, mode='r') as file:
        csv_reader = csv.DictReader(file)
        for row in csv_reader:
            yubikey = {
                "serial": row["serial"],
                "secret": row["secret"]
    return yubikeys

def store_yubikeys_in_auth0(yubikeys):
    url = f'https://{AUTH0_DOMAIN}/api/v2/tenants/settings'
    headers = {
        'Authorization': f'Bearer {MGMT_API_TOKEN}',
        'Content-Type': 'application/json'
    # Get existing settings
    response = requests.get(url, headers=headers)
    if response.status_code != 200:
        print(f"Failed to get tenant settings: {response.content}")

    settings = response.json()
    # Add YubiKey data to tenant settings
    settings[STORAGE_KEY] = yubikeys

    # Update settings with YubiKey data
    response = requests.patch(url, headers=headers, data=json.dumps(settings))
    if response.status_code == 200:
        print("YubiKeys stored successfully in Auth0.")
        print(f"Failed to store YubiKeys: {response.content}")

# Load YubiKeys from CSV file
yubikeys = load_yubikeys_from_csv('C:\Data\python\yubikey\yubikey_seeds.csv')

# Store YubiKeys in Auth0

I’m getting the following error:

Failed to store YubiKeys: b'{"statusCode":400,"error":"Bad Request","message":"Payload validation error: \'Additional properties not allowed: yubikeys,sandbox_versions_available\'.","errorCode":"invalid_body"}'

Does this imply that free tenants do not allow importing hardware tokens, or something wrong with the code?
I did notice that MFA is completely unavailable in the free subscription. Is that somehow related?

Thank you.