Getting plugin tutorial working

Hi, I’m working through this article:

to learn basics of plugin development.
I’m on a Mac machine running Catalina, docker desktop installed and used on other projects.
I started a new terminal window (sitting at my home directory). Followed the first steps in the article, but when I type “pongo run”, I get the following error after creating the container:

Creating pongo-452ebcf4_kong_run ... done

Kong version: 2.8.1

0 successes / 0 failures / 2 errors / 0 pending : **0.000025** seconds

Error → Cannot find file or directory: /kong-plugin/spec

Error → No test files found matching Lua pattern: _spec


Ok, I have no directory called /kong-plugin/spec so that error makes sense, but what am I supposed to do to rectify this??