I downloaded a the ursula hair (despite already buying it.), and got the same error. So, I don't think it's limited to just you.
I'm going to go out on a limb here and assume these are pirated, and seeing as the Daz official version installed just fine for me, I don't think it's a leap to assume that there's something up with the pirated versions of what you're installing. That said, either get the Content Package Assist and repackage the files (may not be smart content, however) or install them manually to your Daz directory.