TLDR; Install the relevant packages for the language you care about like every other guide tells you do to.

By the end of this guide, you’ll have a robust development setup ready to tackle any project.

And by a robust dev setup they mean the bare minimum packages installed for projects in one of C/C++, Python, Java, or Javascript.

If you really want a robust developer setup look for guides and tutorials about the language you care about. This goes into so little detail on anything that it is basically useless.