Go to the official website of the Yandere Simulator: https://yanderedev.wordpress.com/downloads/ here you can always download the latest official version of the Yandere Simulator from the YndereDev.
Link sends to download Yandere Simulator page:
Now you need to choose where to upload the archive to the game on your computer. You can load just on desktop, for example.
If you don’t know how to install the game, click here: how-install-yandere-simulator