Here are steps to download and setup Chromecast App for Laptop :

If you already configure Chromecast App to TV setup we can go to the next step to download and install google chromecast app for laptop configuration.
In your Mac laptop or computer, open https://google.com/chromecast/setup/ and download chromecast app with google chrome browser.
After you click download button, follow chromecast app installation one by one.
After you finish software installation, the next step open the application and chromecast app will automatically search the chromecast device that connected through the wifi.
Congratulation if you on this step, this is the last step after you can found Chromecast device in the network. Now you are done the installation and configuration, happy cast with chrome cast app for osx.