No, the tutorial is asking to add one 4-pieces curved rails, as it results from the images.
Anyway, according to your suggestion, I had to add six 4-pieces curved rails before the tutorial went to next step.
I can see this is not a bug, but anyway it's extremely unclear what is asked to be done.
I ...

Good day.
I'm using the latest Steam version on Mac (upgraded from demo version), no mods installed.
I'm actually not able to get over step 2 in Basic trains & rail building tutorial.
I've been trying several times, and sometimes with a few variations (number of rail elements, rail direction, etc ...