I haven't had time and still don't have time to fix this plugin.
I've optimized it a bit and implement yet another climbing technic but it's still not working so I won't be releasing it... Just wait or fix the plugin/create one yourself.
And the compile error is because you don't have
http://forums.alliedmods.net/showthread.php?t=28284
Could be also that it failed to load because of the new amxx or due to my crappy coding skills.