If you’re getting this error, it’s likely that you are using the wrong key or email address. To ensure you’re not, first navigate to the API area of your my account page:
https://www.kadencethemes.com/my-account/my-api-keys/
Take note of both API and email fields from your account page:
In another tab or window, navigate to your WordPress admin area, and open Appearance> Getting Started. Copy your API from your account, and paste it into the API box. Do the same with your email address:
Click the “Save Changes” button, and you should see a confirmation that your API has been input: