Installer le CMS Contao sous l'application WebApp Custom / Install Contao CMS under Webapp Custom app

Anyone could help me?

When I try to reach https://contao..eu/contao/install, I get a nginx 404 failure whereas https://contao..eu/web/contao-manager.phar.php is working…

I don’t understand why I get this issue. Could it be due to non proper data permissions ?