If you use standalone runner outside of Maven/Gradle, your IDE won't know about packages and classes to make auto-completion work.To mitigate that, manually register webtau-all.jar as a global library. Jar is located in the lib directory next to the webtau executable.

Follow https://www.jetbrains.com/help/idea/libraries-and-global-libraries.html documentation to register webtau-all.jar as a global library.