The formulas question type is a Moodle plugin, so you or your Administrator must install it.
Prior to installing the formulas question though, you need to install another plugin , that is, Tim Hunt's adaptive multipart behaviour, available from GitHub or from the Moodle Plugins directory. Note that you need version 3.3 or newer of this behaviour, because the formulas question will not work
with previous versions.
You can then install the formulas question either from:
the Moodle Plugins directory:
using a zip file
Installing from the Moodle Plugins directory
The formulas question type is available from the Moodle Plugins directory. Install the formulas question as any other Moodle question type plugin.
Installing from a zip file
Download the zip file from GitHub. Unzip the file in the 'question/type' folder and then rename the new folder to 'formulas'.