The shaders in Asset use standard PBR material settings, so all you have to do is drag and drop the material onto the object. Each shader has metallic and specular version.
Note: in built-in version 2020 and older, you won't be able to create or use custom matrix shaders (e.g. transparent and others) without amplify shader editor, because of the lack of support for shader graph. But still you can use matrix effect with PBR.
Before purchase, check the documentation.
Support: izzynab.publisher@gmail.com
*Demo scene doesn't include model of YBot from Mixamo or Spozna scene.