Using Postman getting 401 Unauthorized

I’ve just installed the plugin and setup a webhook to receive data. It shows me the full url and I’ve added the custom action etc.

When I use the Test Action inside the plugin, it outputs the input (using the functions.php filter I added).

But when I try to send data to the endpoint using Postman, it returns 401 Unauthorized error.

But the Authentication tab has no templates. The URL has the api_key like this:
https://mytesturl.com/?wpwhpro_action=update_my_data&wpwhpro_api_key=deprecatedforsecurity&action=custom_action&wpwh_identifier=import_data

I’m confused as to what I’m missing.