VisuStella updates their plugins monthly to fix bugs and ensure compatibility with the latest RPG Maker MZ updates (v1.6.0+, etc.). Pirated packs are usually for version 1.0.0. You will hit game-breaking bugs that were fixed years ago, with no way to get support (VisuStella’s Discord will ban you for asking about cracked versions).
VisuStella MZ plugins are NOT available for free in full. They are commercial products sold by Yanfly's official team for RPG Maker MZ.
Searching for pirated versions of VisuStella plugins is not only illegal; it is technically dangerous for your game project.