If you're looking to Download Duo Mobile on your Chromebook laptop Then read the following guideline.

Duo Mobile works with Duo Security's two-factor authentication service to make logins more secure. The application generates passcodes for login and can receive push notifications for easy, one-tap authentication on your iPhone, iPad, or Apple Watch. Additionally, you can use Duo Mobile to manage two-factor authentication for other application and web services that make use of passcodes. Note: For Duo accounts, Duo Mobile needs to be activated and linked to your account before it will work. You will receive an activation link as part of Duo's enrollment process. You may add third-party accounts at any time. License agreements for third-party Open Source libraries used in Duo Mobile can be found at https://www.duosecurity.com/legal/open-source-licenses.