Opening my app with 'yarn start' : error Command failed with exit code 1

I'm beginner with React. My first app as exercice work well. But for next exercices I have to download a file from GitHub.

This one for exemple

So, I download the file, unzip it, open the unzipped file from vsCode, everything opens, everything looks ok.

I do 'yarn start' as with my first app and this is what is displayed in my Terminal:

What does it mean ?