chouffainet Added some files to _files but nothing is shown.
This is not where you add files. You add files and folders to the same directory as where you have index.php. That's the point. The _files storage dir is created by Files Gallery for storing config and cache, and will purposely be excluded from displaying. This is highlighted in the install docs.
Optionally, you can assign the root config option to read files from another dir. The _files dir is always excluded.