It might depend on which version of WW you are using. But in 2.18, the modelCourse directory comes with what you need in these folders:
https://github.com/openwebwork/webwork2/tree/main/courses.dist/modelCourse/templates/achievements
https://github.com/openwebwork/webwork2/tree/main/courses.dist/modelCourse/html/achievements
So a new course that is a descendant of the distribution model course has what is needed. Another course could just add these folder to its templates and html folders. Then when you use the Achievement Manager (aka Achievement Editor) to import achievements, it will see the default_achievements.axp file and import from that. And all of the files it depends on for individual achievement evaluation are in one or the other of those two folders.