Full Error Message:
Error while creating new document. Error message: Application unauthorized.
Please authorize before trying to access Google Drive.

-You may get this error message when trying to generate a document though your google drive has not  been connected and app unauthorized.

How to resolve: 
You need to do first step in documentation which is to go to “RS Documents Configuration” tab (can access from RS Documents app window or by clicking the + sign for more tabs) and click “Grant access.” Then you will follow the steps to connect your google drive account you would like to use to generate documents.
NOTE: If you find a new error message as soon as you navigate to this tab, please copy/paste the error message and send to support@ramseysolutions.com so we can add your custom domain to our approved list of URLs. With you sending the actual error message, we will be able to see your custom domain name and your server instance.
NOTE: If using Lightning Experience, this 3rd party authorization page is not yet a feature available so you need to be in Classic version to connect the app and then you can return back to Lightning.