Searching for a "free download" of through third-party sites like OnHax presents significant security and legal risks. While Nexus 2 is a highly regarded synth plugin, it was originally protected by strict hardware-based security (USB-eLicenser) that makes unofficial "cracked" versions notoriously unstable and prone to containing malware. Security Risks and Technical Issues
: Nexus 2 was designed primarily for 32-bit systems and is known to be "super finicky" on modern 64-bit DAWs. Cracked versions often suffer from library disappearance or complete VST failure when projects are reopened.
ReFX has replaced Nexus 2 with newer versions, and they no longer sell the older version directly. Support - reFX