Welcome to the unofficial Symfony Micro Edition.
As opposed to the Standard edition, this is not fully functional, and if you've never used Symfony before, you should be using the Standard Edition instead.
This is intended for experienced users of Symfony, and just includes the basics. That way, you don't have to rip out all the demo stuff and bundles you don't need for your project from the Standard Edition every time.
If you don't know how to use this, don't. Use the Standard edition.