By default MFA is disabled on your account. It's really quick and easy to enable it and you have two methods you can use:
1. SMS
2. FIDO
Enable SMS
Go to Profile
Select Multi factor authentication and then select SMS on the dropdown and click Save
Select your country code, enter your number and click Save
Then click the button to Send Confirmation Code to your phone
Enter the confirmation code that you have received - this will remain valid for 10 minutes, after which you will have to request a new code
You'll then be taken back to the main account page and your device will have been enabled for authentication via SMS. This will become active the next time you log in to your account.
Enable FIDO device (Yubikey)
Go to Profile
Select Multi factor authentication and then select FIDO device on the dropdown and click Save
Click on the Register your FIDO device button
You will then see
Please confirm your device by touching the key icon.
Follow the instructions to complete your device registration.