Volná malířská tvorba does not mean painting like Jackson Pollock, it refers to the non-commissioned work that the artist does. This guy's website
http://www.stoneage.wz.cz/tck/ perfectly demonstrates this: he has one page with his commissioned illustrations, one page with comic strips, one page of "volná tvorba" including images he made on a computer (check out the one of the guitar strings, definitely not "drawn by hand without using any special tools), and then some websites that he did. His volná tvorba is the work that he was not commissioned to do, they represent his own ideas and are his independent work.