material library is still in development state for Corona in Cinema4D, with its plan to be released with the next version, V7.
Stay tuned for future daily builds if you’d like to get your hands on materials sooner than the release, or you can try some of the Physical Material presets, which are already present in the latest V7 Daily build.
As mentioned in the blog, being worked on - since the Max team is developing the Physical Material, they have to finish their work and release it, before integration into C4D can begin. So, “as soon as we can”