Cakephp 3.2 installation

Hello,
No, I didn’t restart it, but I installed twice a cakephp project (
http://book.cakephp.org/3.0/fr/quickstart.html) and I got the same error.
I downloaded it again today, throw the composer utility and it’s fine, I
properly installed it.
I fail to understand where is the problem, but anyway, thank you.
Cordially.