Installation on El Capitan Using "Mac Server" App


So I'm having trouble installing on a Mac using "Mac Server App"

I’ve installed and unzipped SuiteCRM into /Library/Server/Wed/Data/Sites/Suite

But when I enter chgrp _www._www /Library/Server/Wed/Data/Suite -R

I Get Illegal Group Name error

Any thoughts on how to resolve this? Should I install in a different directory or am I missing something.