It works almost well ;-)

In the project of your https://console.developers.google.com/

I've just get the missed parameter :

1. create your "consent screen" and input your "product name"
2. then, create your credentials

The "sync Google" in crm.meeting raise an error, but the cron sync meetings.

I suggest to adapt the explanation in the tutorial.

As Bruno Joliveau mention, you need to create a fake ap name, add your email adress and save in the consent screen menu, once credentials are filled in. then synchronisation works

Thanks Bruno

Error 401 means that you are not authorized to view the page. In some cases, when trying to address a wrong URL, this shows up. Make sure that the url used is correct (inc. port number and perhaps even protocol). If it is correct, make sure the credentials are correct. Try to manually login and see if that works.

If all of that fails, check which version of Odoo you are using. It might be a bug in the code then.