Can I still download OS X Mavericks for Free?
Yes, it is still possible to download Mavericks: http://www.techspot.com/downloads/6268-mac-os-x-mavericks.html

That is a upgrade from Mavericks 10.9.4 to 10.9.5 (not a full version of Mavericks which is a 5.3 Gig file.)

But maybe the software not working on Yosemite may neither works on Mavericks.