To create a new panel, you can use the make:filament-panel command, passing in the unique name of the new panel:
php artisan make:filament-panel app
This command will create a new panel called "app". A configuration file will be created at
app/Providers/Filament/AppPanelProvider.php. You can access this panel at /app, but you can customize the path if you don't want that.
Since this configuration file is also a Laravel service provider, it needs to be registered in config/app.php. Filament will attempt to do this for you, but if you get an error while trying to access your panel then this process has probably failed. You can manually register the service provider by adding it to the providers array.