Since 2016 the work of OS maintenance and development has been taken over by members of the 2011 committee in the Shen Language Open Source Community.
To get going quickly you can install these binaries for Windows and Linux for Shen under Common Lisp.
Also binaries for Windows, Linux and Mac OS for Wasp Lisp.
You can find a complete list of downloads on Github; https://shen-language.github.io/. The Shen certificate placed against the port indicates that it has been tested as conformant to the standard test suite distributed with the sources.