Module doesn't work correctly

I installed the module and it seems that it doesn't work. When I set variable $environment_users_per_environment or $environmen in settings.php and choose the environment for some users on their profiles that users can log in to all environments of the site. I checked code and found that the global variable always returns 'NULL' instead of the expected type of environments. To fix that problem I am suggesting to use $conf['users_per_environment'] = 'type of env'; in settings.php