How to Set up Authy for Two-factor authentication (2FA)

Step1: To begin, install the mobile version. To do this, go to the iOS App Store or Google Play Store and download Authy as you would with any other app. Make sure to download the official version by Twilio.

Once downloaded, launch the app and you will be greeted by the main setup screen.
This screen will ask you for your country code and phone number

Enter the phone number for your device, then confirm. At this point, Authy will then need to verify your phone number by either
sending a text message or an automated call. Once you receive the confirmation via SMS or voice call, enter it into the field provided.
           


Step2: Setting up your accounts to use Authy for 2FA, this process will vary slightly between different platforms and websites,
but ultimately, it’s the same across all sites. For this example, we will be using GitHub In GitHub — go to the Settings area for your account.



Step3: From there, click on Passwords and Authentication. In some menus, this option will be called Security.



Step4: On the next page, select Enable Two-Factor Authentication.



Step5: At this point, most sites will ask if you want to use an app such as Authy or use SMS. In this case, we will select Authy.



Step6: You will then be presented with a QR code. This is the code you will scan from the Authy mobile app to link the two applications.



Step7: Return to the Authy mobile app. If this is a new install, the app will only display a “+” icon.
Click this to add a new account. Otherwise, click the top right menu and select Add Account.



Step8: The app will then tell you it’s ready to scan the QR code. Click the blue bar that reads Scan QR Code.



Step9: Then simply use your phone’s camera to scan the QR code on the screen.
Authy will recognize the QR code and present you with a six-digit PIN code to enter into the website.



Step10: Using Authy on desktop and syncing devices
Now that Authy is set up on your phone, you’ll want to add your desktop computer so that you can log into sites without the need to
always have your phone handy. Begin by clicking the top right corner in the mobile app and clicking Settings.
You will then want to click Enable Multiple Devices.



Step11: Once done, go to the Authy website on your desktop browser and click the download link at the top of the page.
Then select your operating system either macOS or Windows. Once downloaded,
you will install the program as you do with any other application on your computer.
At the first screen, once again enter your phone number. Make sure it’s the same one you used to set up the mobile Authy app.



Step12: Once entered, the Authy app on your phone will be notified and alert you that a new device wants to be synced to the account.

You will be asked to confirm this sync by manually typing OK.  Do this and then you will receive a confirmation page.
The process is now complete and your desktop Authy is synced with your mobile version.

All accounts added with one device will be instantly shared across all devices you add.



Step13: Remember to enable backups for Authy

There is another crucial step when using Authy that is sometimes not enabled by default. This is to enable a backup password.
This is one of the most important steps, because if your phone or device is lost or damaged,
there will be no other way to retrieve your accounts other than using this password.

To enable this feature, go to the top right corner of the mobile app and select Settings. From there, click on Enable Backups.



Credit : https://www.techrepublic.com/article/how-to-use-authy/