Azure Function - You do not have permission to view this directory or page.

I have created an azure function and required that the authentication to be of type "Function" When I try to view this function in browser like the following: 

https://myfunctionapp.azurewebsites.net/api/myfunction?code=dJHl33LeP6zYUnHA

I got the url above from my azure function when I copied the url of my function, however, I get the error: You do not have permission to view this directory or page. ..

I am following a tutorial like in this video: https://youtu.be/uST0CyqRIHA?t=846 

Video starts at the time where he made a request to Azure from postman and it was successful. What am I missing here? One thing I can think of is that the key am using is much shorter than the one in the video am not sure why. 

Thanks.