I noted when I was doing the tutorial, that not all the playground examples ran, which was a bit of a frustration.
But it makes good practice to take the lesson into your own codes and run it there.
I found I learnt more doing that because I had to make an effort to remember the syntax.
Frustrating I know, but not all bad.
Given time, I am sure Sololearn will produce an updated version resolving these issues.