Your tutorial is not for Twine, which is an IDE/compiler, but rather for the Twine 2 compatible story format, Harlowe.
The distinction is important as there are multiple versions of Twine and multiple story formats for each version—e.g. Twine 2 comes bundled with Harlowe, Snowman, and SugarCube. Most story formats use a somewhat different syntax relative to their contemporaries, so that makes the distinction of paramount importance. The code in your tutorial only works in Harlowe.