Forewarning I'm not a Wordpress user. But this error sounds to me like an incorrect setting. I'm not sure how you "enabled recaptcha" but if you have admin access to recaptcha where you can specify which domains are used for the recaptcha then that is where you'd want to go.
You'll want to create or update the site key as the error mentions.
If you're logged into your email associated with recaptcha you'll want to go to this link/screen
If your site is already in here, then just click on it and view the keys like this:

Other wise create a new one and replace the site key/secret key in Wordpress.
