When Access Manager is enabled, requests must be signed using a secret key. PubNub SDKs handle signing of the requests for you, automatically.
If you choose to use PubNub REST APIs instead of an SDK, you must generate the signature and add it as a query param on your own. To do this, please follow Signature Generation in Access Manager.
Additionally, you can reference the source code of a PubNub SDK and leverage it in your application. For reference, see our Python SDK signing method.