OpenClipArt has been down for about six weeks now. The best searchable fallback I’ve found is Public Domain Clip Art which has 13,778 bits of clipart under Creative Commons or Public Domain, though that’s only a sub-set of the apparently 150,000 bits that OpenClipArt had at its demise. So far as I can tell, after extensive searching, no-one was keeping a full mirror or tarball of OpenClipArt at 2019.
Carrara 8 is DAZ Studio's official 'big sister' software.
Carrara loads all DAZ and Poser characters and scenes,
and supports LuxRender for top-quality realistic rendering.