FoldSynth is offered as a zip file, containing executable Java code as well as shell scripts for launching the program in Windows or via Bash in OS X / Linux.
A recent version of Java should be the only pre-requisite. To run, unzip into a directory of your choosing and execute either “FoldSynth.cmd” (for Windows) or “FoldSynth.sh” (for OS X / Linux). Note that on non-Windows platforms it may also be necessary to add execute permissions manually.