Roc's initial release is still under development, and this website is a placeholder until that release is ready.
In the meantime, if you'd like to learn more about Roc, here are some videos:
To set clear expectations around Roc's readiness for serious use - it's not ready yet! - the repository where it's developed is private for now.
Anyone can get access to the repo in this way, or you can download a zip of the source code, although the zip isn't updated very often and is definitely behind what's in the repo.