2-FA is mandatory for all users to exchange at CoinDeal. It helps us ensuring that you are the only person with access to your account, even if someone knows your password.
Authentication app needs to be downloaded on your device, e.g. phone.
You will receive a Secret Key (write it down in a secure place). Open your “Authenticator” Application and add a new key. Choose an option “Scan barcode” and use your phone to scan the code displayed on a website. The app will give you a 6 digit code which you need to write down on a CoinDeal website. Remember that the code changes every 30 seconds.
Here is an explanation how to set up a Google Authenticator on a different device: https://support.google.com/accounts/troubleshooter/4430955?hl=en#ts=4430956