You need to download the installer provided on the Flyforhero.net website. The installer is about 800MB+. So it will only take up about 0.37% of space on your hard drive (if my "count on my toes" math is right), so I'd say you have plenty of space ^_- Do not install this in your Flyff directory. It needs to be installed in its own folder.
And just to help you out on any issues you might have in the future with diskspace:
1 GB= 1024MB
1 MB= 1024KB
1 KB=1024B
1 B= 8 bits
215GB = 220160MB
(X*100)/220160 = % used on your harddrive
X=MBs an application takes up
Brb, gonna go clean my star trek figures *snorts*
:B