The current release of Clozure CL is version 1.12.
All versions include both 32- and 64-bit binaries (except for ARM, which is currently 32-bit only).
Please see the installation page for details on completing the installation.
32-bit x86 ports need SSE2
The 32-bit x86 versions of Clozure CL depend on the presence of the SSE2 instructions. Most x86 processors manufactured and sold in the last several years support SSE2 (all Apple Intel-based Macs do, for instance), but there are some exceptions.
The Wikipedia article on SSE2 lists processor models that support SSE2 (and also notes some of the more notable exceptions).