You have to create a QGIS project (.qgs not .qgz) and a Lizmap configuration file with help of the Lizmap plugin. Put those files in a new directory created in lizmap/instances/.
Note that there are yet two directories
test_france_partsandtest_france_parts2if you just want to test everything is ok before creating your own project.
Then, in the administration page, declare a Lizmap repository pointing on one of your directories (it should be visible in 'Local folder path' dropdown) : http://localhost:8090/admin.php/admin/maps/editSection
Then you should see your repository and project in the main Lizmap page.