1) Go to https://www.google.com/recaptcha/admin/create (log in if necessary):
2) Fill in your marketplace name as an identifier:
3) Choose reCaptcha v2 "I'm not a robot" Checkbox as a type:
4) Fill in your chosen domain in the next field and then hit Enter:
Make sure to NOT write in the protocol (http://, https://, www.)
5) Make sure that you accept the Terms of Service and click on Submit!
6) In the next screen, copy the Site Key by clicking on the COPY SITE KEY button:
And then fill that text into the Google Captcha Key field in your marketplace's Admin Panel > Company Info, and hit Save:
Make sure there are no extra spaces before or after!:
Note: if your marketplace is from the old version of our site (e.g. your original URL before connecting a domain had a format like "https://mtmarketplace.azurewebsites.net/Site?name=yourmarketplace") you ALSO need to add the Secret key in the same way as the Public one.
And that's it!