To use this .unitypackage , you simply drag and drop it into an open Unity project. It is highly recommended to of Poiyomi from your project before importing a new Pro build to prevent GUID conflicts and shader errors.

The package refers to a specific professional version of Poiyomi Shaders , one of the most advanced and widely used shader suites for Unity, particularly within the VRChat and 3D avatar communities. Overview of Poiyomi Pro

The versioning 7.3.50-8.1.140 typically indicates a transitional or cumulative update that bridges the features of the 7.3 stable branch with the advanced 8.1 architecture.