What is an Application Limit Error?
What does "you've reached your applications limit mean"?
This can happen if you've created tests with a different domain name than the one you're creating a test for now. Free users are limited to 1 domain, so that's why you see this error. You can delete the app and create a new one- just go to the drop-down menu in the top right corner of the page, or go to https://loader.io/targets and delete the one that's already there.