Hi @bwalsh , welcome to the Auth0 Community!
Your Professional Subsciption will allow the use of “Pro-MFA” Factors. These are either the OTP with an Authenticator App, or Cisco DUO Security.
The factors that have the text “Enterprise MFA” will need an Enterprise Subscription, configurations can be made but you’ll likely see a warning that the feature requires an Enterprise Plan.
So to confirm, SMS Notifications as a factor would require an Enterprise Subscription. Please take a look at the Auth0 Pricing here for more information and comparisons between the plans,
thanks!