not working with single WP install on subdomain

[olivierhaustrate]

Thank you Sébastien for this great plugin. It works perfectly ... except on subdomain.
I've setup a subdomain (dev) for staging on a production server of one of my client, and don't get your plugin to load the require mu-plugins listed in composer.json.
I'm working with a single WP install and I've added mu-require.php inside the mu-plugins folder.
Could you help me make it work on subdomain?
I don't know if I need to change some config on the production server (Apache) or if I need to change something in your plugin... I'm lost.
Thank you in advance,
olivier