Azure MFA is a two-factor authentication feature that is included in Azure AD Premium and Enterprise plans. It was announced in March 2017 that Azure MFA would be discontinued as of June 30, 2017.
Customers who need Azure MFA should contact their account manager to upgrade to a Premium or Enterprise plan. Azure MFA is not available in the free tier.
This discontinuation of Azure MFA comes as a surprise, as the feature was announced just two years ago. It is possible that Azure MFA may be reintroduced in the future, but for now it is gone.
Customers who need Azure MFA should upgrade to a Premium or Enterprise plan to continue using the feature.