There is no quick steps to enable mfa for guest users via this UI.
If you choose your tenant users, the button will show up.
If you want to enforce multi-factor authentication for B2B guest users, you can follow this tutorial.
Trying to activate MFA per user as described here https://docs.microsoft.com/en-us/azure/active-directory/authentication/howto-mfa-userstates#enable-azure-mfa-by-changing-user-state however
Install-Module MSOnline but then Connect-MsolService runs into Connect-MsolService : The term 'Connect-MsolService' is not recognized as the name of a cmdlet, function, script file, or operable program.How can MFA be enabled per user in AAD?
There is no quick steps to enable mfa for guest users via this UI.
If you choose your tenant users, the button will show up.
If you want to enforce multi-factor authentication for B2B guest users, you can follow this tutorial.