I'm sorry to necro such an old topic, but I' was trying to do the same and all I managed to do was to get to a blank page that invited me to create the new page.
The link to media manager is
https://knucklecracker.com/wiki/doku.php?id=cw4:info:start&do=media&ns=cw4%3Ainfo
and I wrote it on the wiki page as:
[[ cw4:info:start&do=media&ns=cw4:info | Media Manager]]
Now I'm sure I'm just overlooking something trivial, but any help will be appreciated.