To configure the Google Invisible ReCaptcha extension you will need a site key and a secret key. Follow this short guide to get them correctly.
1. Open this page and fill in the name of your website;
2. Select the Invisible ReCaptcha option from the list of the available variants;
3. Specify the domain of your website;
4. Tick the Terms of Service checkbox;
5. Hit the Register button.
Now, you can copy the keys from this page to your Google Invivisble ReCaptcha configuration section.