While Endeca isn't free, you can still download it from Oracle's software delivery cloud: https://edelivery.oracle.com. You'll not be able to use it in a production environment without purchasing a license from Oracle.
@PaulLemke had good links to the contacts and docs. If you want to ask questions, you can either use My Oracle Support (for paid customers) or the free forums on OTN: https://forums.oracle.com/forums/category.jspa?categoryID=514.