You might need to provide some context, as it is not clear what you are trying to do here?
By following the guides you mention, you would have first created an API definition and then used a policy to control access to that API.
You should now be able to connect to that API, using the access credentials you created, there would not be a button for connecting to an API though. You would connect to the API via code in your application, or using a client like Postman, etc.
Or have I misunderstood your question?