You must use the actual IP address (instead of "localhost") for the Web API URL.
Reason is in the section called “Recording scripts automatically (using Recorder)” and the section called “Recording scripts manually (using Fiddler + JMeter)”, you will use the JMeter proxy server or Fiddler (or any other web debugging proxy tool) both of which will bypass "localhost".
If you have not configured and deployed any PowerServer project before, you can practice by following Quick Start > Guide 1 to deploy the Sales Demo application. This guide will take the deployed Sales Demo application as an example to walk through the test script recording and parameterizing/correlating.
