Using OAuthTokenGenerator - jimper/googleads-dotnet-lib GitHub Wiki
#Introduction
OAuthTokenGenerator is a Windows application that is distributed with Ads API .NET libraries. It allows you to generate a refresh token when you use a Native application flow while implementing OAuth2 protocol for your application.
To get this application, download the latest binary distribution of the client library, and look within \lib folder of the zipped file.
#Create an OAuth2 client ID
Follow the instructions in this wiki article to create a project on the Google Developers Console, and create an OAuth2 client ID for a native application.
#Generate a refresh token
Start OAuthTokenGenerator.exe. The welcome screen is as follows:

You need to provide the client id and secret you obtained from the above step. You also need to choose the APIs that your application plans to use. Tick all that apply. Now click OK.
Note: If you are working with Location Extensions in AdWords API and need to populate the OAuthInfo field of
PlacesLocationFeedData, then select the 'AdWords API' Scope on this screen.
This will bring up a login screen. Login with your Google account credentials.

Once you sign in, you will be presented with a Consent screen:

Click the Accept button to accept the request. OAuthTokenGenerator will complete the flow and present another screen with the necessary configuration.

You need to copy this configuration to your App’s App.config / Web.config.