Cwk3D's Color Material Library
Can these materials be used in earlier versions of Blender?
Yes. The included Blend file, while created in Version 3.2 it does open in version 3.0 and 3.1. However that isn't necessary if the material library is installed as per the instructions.
For version 2.93 the included Blend file can be appended and if just the material folder is selected the materials will become available in the material dropdowns in the Shader Editor.