All source releases and some binary releases are listed at the sourceforge download area under the link show above. The sourceforge file area is replicated all over the world and should be accessible with highest bandwidth in all corners of the world.
Do not use 0.10.x anymore! It is listed as stable since it is the only release of zziplib tested to work on a few dozen platforms. However there were some problematic zip files out there that can trigger segfaults. Later zzip file decoders have extra checks and helper routines for that. It's just that the later zziplib have not been given as many crossplatform build tets as the 0.10.x generation.
Use a 0.12.x (proto-stable) or a 0.13.x (developer) variant of zziplib, especially if you intend to make heavy usage of the zip decoders in specialized environments - I will not add any fixes to the 0.10.x series anymore (it's deep frozen) but if you hit a problem with 0.13.x I can help you quickly with a patch and official bugfix release. The later versions are regulary checked crossplatform atleast for Linux, Solaris, FreeBSD, Darwin/MacOSX, Win32/NT including i386, amd64, sparc, sparc64, powerpc where available.
Note that all generations 0.10.x through 0.13.x are strictly backward compatible. There is a core API (file and dir handling) being binary compatible, which is also true for most of the helper routines (data getters). Only some rarely used entries are made source level compatible, and so far no one had ever any problem with binary compatibility of the zziplib DLLs.
The MSVC users are strongly advised to use a a later version as well since I have tested the 0.12.x/0.13.x myself and making some msc binary dll releases directly - prior versions were thirdparty contributions which were working smoothly since I have been preparing zziplib for win32 using the gcc/mingw compile suite. Please check also the developer pages.