Errors in DevTools console

I’m getting these errors in the Console when using this plugin:

(index):1 Access to XMLHttpRequest at ‘https://static.mailerlite.com/css/universal.css?v4’ from origin ‘https://www.wpminder.com’ has been blocked by CORS policy: No ‘Access-Control-Allow-Origin’ header is present on the requested resource.

cs.js:284 GET https://static.mailerlite.com/css/universal.css?v4 net::ERR_FAILED