Project page: https://davinci.fmph.uniba.sk/~michalovic26/rocnikovy-projekt/index.html
If you just want to try the program, versions for Windows, Linux and web are available on the abovementioned project page. If you want to try and build and run it yourself, you can do it with
a) Unity - this project was made for Unity 2020.3. Download all files except the folder ConsoleVersion and add it to your Unity project
b) console version - download only the Assets/ErosionSimulator and ConsoleVersion folder - these contain the library + a console user interface.