Hello, I am using the sdk 'ringcentral_sdk'

Can anyone help me understand what I am doing wrong here?

I have attached a screenshot of my code, I am only trying to get the authentication.  
Note => I have removed sensitive information.

Based off of the docs found here   https://ringcentral-sdk-ruby.readthedocs.io/en/latest/usage/authorization/Authorization/#using-oauth...   
I have also tried this.

Please note that the documentation is using either older code or wrong use of the RingCentralSdk module.  

::Sdk and ::Platform are uninitialized constants.