google-ads-python | Google Ads API Client Library for Python

I've set up the whole Google Ads API according to this manual here: https://developers.google.com/google-ads/api/docs/client-libs/python/oauth-desktop?hl=en

I got my refresh token and put it in my google-ads.yaml file which looks exactly like this: https://github.com/googleads/google-ads-python/blob/master/google-ads.yaml. I also put my client_id, developer_token and client_secret at the corresponding spots in the file.

Everything worked out and I could for example ask for all campaigns: https://developers.google.com/google-ads/api/docs/samples/get-campaigns#python. Also I could use other services of the API.

Each time I use the API I access it via the client using the following code:

I am trying to work with Google-ads-API. Running Ubuntu 20.04, Python 3.9(min requirement for the client library to work is 3.6), working with google-ads-api V6. Here's the story of my agony.

I have made a test manager account[A], generated a developer's token, and have "test-level" access to use the API, which is great. Test level allows you to make calls to the API regarding information\reports dealing with test accounts(not production).

Also, went through the whole Oauth2 credentials for account [A], allowed test emails, and after running "examples/authentication/authenticate_in_web_application.py", I am redirected to a webpage, allow my main test manager account to access the second test manager account[B](as instructed by the documentation, to create another test manager account[B], besides the main account[A] with the developer token), a refresh token is generated successfully from this OAuth2 prompt, to allow account [B] to be managed my account [A], added the refresh token to my google-ads.yaml file, and things are all good.

When I run this .py file from the examples