Since a direct 1:1 emulation is unavailable, several modern plugins specialize in the physical modeling and "deep digital" character the Z1 was known for:
The Korg Z1 is a physical-modeling synth originally hardware-based; a VST version commonly refers to software editors/emulations or using the Z1 hardware as a MIDI-controlled sound module via a VST editor. This guide covers finding emulations/editors, installation, DAW setup, basic workflow, patch management, and troubleshooting. korg z1 vst