Why is no contributory theme included on Drupal8-rc3?

Question

Drupal

I installed drupal 8 rc3 today, which is sort of like a green version (not a red one).
Bartik - default theme - works fine.
I clicked "Install a new theme" in the admin panel and on the /admin/theme/install page I
specified archives of 8 versions for the Personal Blog Theme - which is alpha1 (also green) and Prius - which is beta4 (but for some reason yellow here).
after activation - the site is just white without styles at all.
tell me where to look?