Figured it out
Really should have known, but it’s a C++ project so you have to build the project files for it (and it means you need to have Visual Studio installed)
After following the steps above, right click on the ChaosDestructionDemo.uproject and select “Switch Unreal Engine version…”, pick 4.26Chaos from the list and wait for it to build the sln. Now you can launch the project and it will correctly build the module.
Perhaps this should have been obvious but I think it should have been included in the original post.