I've been trying to test an older version of this extension on a private wiki. I've seen that it's installed on the Special:Version page, but it's not showing up on any other special pages. I also have the 'wikifactory permissions. Why doesn't it show up?
Wikifactory is a staff tool - so you would not have permission to access that on Wikia. Special:Version lets you know what version of Mediawiki your wikis is running. You should be able to see that on your wiki.
I believe he's trying to run it on an external Wiki, not on Wikia. He probably got the WikiFactory source and enabled it (which can be confirmed in Special:Version). I don't know if you can run WikiFactory on a non-Wikia wiki though (without any modifications at least). Looking at the source, it relies heavily on Wikia classes to run.