Hello Lorenzo Zambelli
Good day!
As I see from the previous comments that you are navigating to the users authentication methods. but as Ankush Raj proposed that to enable the email otp for users below are the steps to perform
Login to portal.azure.com or entra.microsoft.com
2.Select the Microsoft Entra ID
3.Select the Security > select Manage > Go to the authentication methods
4 Now you will see list of authentication methods enabled in you tenant
5.To enable the Email OTP as authentication method, configure to yes.
Hope this helps. Do let us know for further queries.
f this answers your query, do click `Accept Answer`
and `Yes`