The qBeta System (QBS) is stored in GitHub as part of The Beta System (MBS).
The GitHub repository is https://github.com/olmadsen/beta-system
You will need to clone the full Beta System, but you do not need to be able to run Beta programs. The README file has instructions for installing QBS as well as MBS.
The qBeta compiler is called qbeta.
In addition to the compiler, QBS also contains an SDE called qenv.
MBS and thus also QBS are only available for Windows 11. It used to be running on 32-bits Linux, which is no longer available. We hope to be able to get it running on 64-bits Linux. For MacOs, you may run MBS and QBS in a Windows 11 on top of Fusion.