About the only thing you'll find are some random choir soundfonts/sfz. Kontakt Player instruments require licensing fees, so the freebies for it are very "unique" and rare, and no one is doing a choir that way. BigCat has a choir wrapped as a VST I think. Search here for Sonatina Choir
http://bigcatinstruments....igcat-maize-vstis.html Pretty sure there was something on KvR that comes as a Kontakt instrument, but it won't work with the free player. Google might help there (and help find soundfonts with choir patches)
Cakewalk's Rapture Session has a Melotron Choir patch. DimensionPro might have some patches too. But nothing I'd recommend. Some of the bigger sampler have libraries that come with some kind of choir (Sampletank/UVI Workstation/etc) but most aren't free (or if they have a free version it doesn't include the choir).