CyPhyAssure
This is a meta-repository for all the CyPhyAssure tools for Isabelle, including Isabelle/UTP. It includes submodules for most of the repositories, and a ROOTS file, which imports all the Isabelle sessions. It also includes a slightly adapted version of the AFP, to provide all the dependencies.
To use this repository, you'll need Isabelle 2021-1 from the Isabelle website. Next, clone the CyPhyAssure repository and make sure all the submodules are checked out. Then, start Isabelle 2021-1 with the command isabelle jedit -d path/to/CyPhyAssure -l Session_Name. Here, Session_Name could be something like UTP, Z_Toolkit, or Z_Machines. Isabelle should then proceed to build the requested session.