The Correct Writing question type focuses on learning grammar of a new language. It can find various mistakes in student's response and give mistake messages and hints. The set includes the other plugins that are required for the question type to be installed.
If you have troubles downloading and installing all individual plugins, you can download full set from our Bitbucket site. The archive correctwriting_xx.zip should be unpacked in the main moodle directory, it will place all plugins where they belong.