Here is the URL: http://chromedriver.storage.googleapis.com/index.html?path=2.21/
Once downloaded you need to install the Chrome driver and set the path of the chrome driver in the path of the system.
Once the Chrome driver is up, the following screen will be displayed:
Also, before working on the chrome browser make sure you have downloaded the chrome driver which is compatible with your Selenium version and your browser.
Just for reference, the following is a sample script for UI automation using the Chrome driver: