If you bought this asset pack on the Unity Asset Store, you can use the package manager to install it. If you got it on itch.io or Gumroad, then you will receve a .unitypackage file, which you can install via Assets -> Import Package -> Custom Package. When you download this pack from any storefront, all the assets will be contained in the Shader Toolbox folder.

Using the shaders

Create a new material and pick any one of the shaders in the pack from the drop-down list at the top, which will be in a subfolder named Shader Toolbox. You can then tweak the settings of the shader and attach it to any object.

If you want to use the _CameraTransparentTexture for any of the transparent effects, consult the documentation page for that effect.