Then I made a collection with the collection maker - in game this is an empty collection.
I don't know anything about the collection maker...isn't that an old program?
The mesh file that can be downloaded here, is a package file and should be placed in your download folder for the sims 2. If you want to test it in your empty testing game, please do.
And in your game why don't you make your own collection file within the game instead?