I also use the free version.
You can try to contact DANewman in the Cineform thread.
Maybe PM him or me your commandline, to check if smth. is wrong there.
If you correctly placed raw2gpcf and there is no problem with your install, you might miss some prerequisites, he told me to try dependency walker when I was having problems.
Also check your source file. He posted a 5D3 source file some time ago in his thread when I was having problems.
I could transcode his source, and then I sent him some of my files to test, so he could update the software.
