Sorry, but crazedgiggles is exactly right. Any downloads that need a .dll file will not work on the Mac because it's a file format it does not understand. Even if you change the extension it doesn't work...you'd have to find a way to convert the file.
Unfortunately, because the Mac version of ZT1 was made by a 3rd party company, they never even converted Blue Fang's own bonus downloads for the Mac version, so there aren't any examples for other creators to work off of.
However any of the downloads that don't need a .dll file will work with ZT1, including the user created ones, many of which will soon be available again here!