Go to the and click 'Download Launcher' link.If you have any issues with it, try downloading the archive with the game files directly. Please note that launcher was developed by another developer and sometimes may work unstable.
You can find installment instructions for those programs in web. If you don't see 'extract' option when you right click on the archive, you need to download an archiver, such as WinRAR or 7zip. You may need an additional software to extract an archive in both cases.
There are two ways of installing Yandere Simulator: