2FA is way of protecting your account. To set up your 2FA you will first need to log in to your Knaken account. In your account you can click 'account' on the left and then '2FA'. Here you will see a QR code and a back-up code in text. You can scan this QR code with an Authenticator app like Google Authenticator. You can also copy the back-up code and paste it in the Authenticator app. After you've done this, a code fill appear in your Authenticator app. Fill in this code into the Knaken panel. After you've done this your 2FA setup will be complete!
When you log in to your Knaken account and it asks for a 2FA code, it means that you've setup your 2FA code. Open de Authenticator app and fill in the code it displays in the app into the Knaken panel. This code changes every 30 seconds, so you will need to type it in within 30 seconds.
If you get a phone or if you delete the Authenticator app, you will most likely lose access to your 2FA code.
If you've lost access to your 2FA code, you can send an e-mail to firstname.lastname@example.org