How to configure Google chat channel

Go to your Google Chat Desktop or Web app.
To create a new space click on the top left corner New chat.
Click on Create a space.
A form like this will appear, named as you desired, choose Announcements for the What is this space for? section and in Access settings you can choose the options as you needed. you can choose the options as you needed. Then click in the Create button.
Select the recently created space.
Click on the name of the space in top left corner and then in Space settings.
Select Apps & integrations.
In the page that appears go to the bottom to see the Webhooks sections, click in Add webhooks.
The next form will appear, type a name for the Webhook and then click in Save.
To get the url generated for the webhook click on the three vertical dots to show a context menu and then click in Copy link.
Finally paste that url into the URL input and click in Save.