Thank you for posting this in Microsoft Q&A.
When you sign up for free version of Azure, you can also sign up for minimum Entra ID P1 license for Azure active directory.
One of the prerequisites for Conditional access or MFA is Entra tenant with Microsoft Entra ID P1, P2, or trial license enabled. If needed, create one for free.
Once you have the free version license, you can follow below article to configure conditional access with MFA for users,
www.portel.azure.com and www.entra.microsoft.com both gives same experience while configuring conditional access.
Earlier we used to call it is Azure active directory which was part of Azure portal. Now we are separating Azure active directory with Azure and it is not called as Entra ID portal.
You can configure conditional access in any of above portals.
Let us know if you have any further questions.
Please "Accept the answer" if the information helped you. This will help us and others in the community as well.