These tutorials are based on the older SketchUp 8, not the new web based versions.
I drew all my plans with the free Sketchup 8 from 2012 and
continue to use that version. If you have the older version 8, I recommend sticking
with that. If you know someone who has Sketchup 8, ask them for a copy. It's only 35 megabytes.
On Jay Bates's SketchUp page you will
also find a link to download the old version 8.
Sketchup versions from 2013 onwards only allowed you to install the much larger
full pro evaluation version, which after 8 hours of usage disables the "pro only" features,
but leaving you with much more stuff on your hard drive.
And at some point the free version became a version that only runs in your browser.
I only briefly tried the web version and didn't like it, though it's a good if you only
want to view an existing cad model.
Up until 2020, you could still download the old version 8 off the SketchUp website,
but I think they removed that to force you to use a newer, less straightforward version
and annoy you into paying for something better. But as of 2021, I still use the old
version 8 myself.