You need to know how the API is normally invoked. You will likely need to identify the API key parameter, choose “custom,” and match the parameter.
If you have the documentation for the API you are calling it will likely include a few code examples for making an authenticated request.
The most straightforward to understand is a curl call, so I’d look for that first.
If you share what API you’re attempting to connect to people will be able to help more.
Edit:
Also, authentication isn’t handled in the schema, there’s a setting you need to adjust to choose how to authenticator with an API key.
