GoogleIotCoreとRaspberry Piを連携させたい

Question

以下サイトの手順に従ってGoogleIotCoreとの連携をさせたいと思っています。

https://qiita.com/shuichiro/items/ea583897bf6ce5eae536

$ python cloudiot_http_example.py --registry_id=(レジストリID) --project_id=(プロジェクトID) --device_id=(デバイスID) --message_type=event --algorithm=RS256 --private_key_file=(秘密鍵へのパス)/rsa_private.pem --cloud_region=(プロジェクトがあるリージョン)

上記を入力した段階で、

Creating JWT using RS256 from private key file rsa_private.pem
Error getting config: 400, retrying
Error getting config: 403, retrying
Error getting config: 403, retrying
Error getting config: 403, retrying
Error getting config: 403, retrying
Error getting config: 403, retrying
Error getting config: 403, retrying
Error getting config: 403, retrying
Traceback (most recent call last):
File "cloudiot_http_example.py", line 266, in <module>
main()
File "cloudiot_http_example.py", line 225, in main
jwt_token,
File "/.local/lib/python2.7/site-packages/google/api_core/retry.py", line 286, in retry_wrapped_func
on_error=on_error,
File "/.local/lib/python2.7/site-packages/google/api_core/retry.py", line 206, in retry_target
last_exc,
File "~/.local/lib/python2.7/site-packages/six.py", line 738, in raise_from
raise value
google.api_core.exceptions.RetryError: Deadline of 60.0s exceeded while calling <functools.partial object at 0x75984930>, last exception: Not OK response: 403

となり403エラーになってしまいます。