Can't start Google Assistant SDK addon in hass.io

Hi!
I get “[Error] You need initialize GoogleAssistant with a client secret json!” when I press start.
I have followed this guide https://www.home-assistant.io/components/google_assistant/ to setup things.
My addon config looks like this:

{
  "client_secrets": "google_assistant.json",
  "project_id": "hassio-a8e1c",
  "model_id": ""
}

Where do I get google_assistant.json? And in which folder do I put it?
What should I put in “model_id”?

Thanks in advance!

Hello, I have the same problem.
Have you solved it?