You might have noticed that if you now setup a new Dynamics 365 trial environment, users who login are greeted with "Help us protect your account" which requires to setup multi factor authentication (MFA) even for accounts in trial/demo tenants. This is part of the Azure Active Directory security defaults.
To get rid of this setting you need to login to https://portal.azure.com and change this setting for the Azure Active Directory used by your demo/trial tenant. Navigate to Azure Active Directory in your subscription and select Properties in the left navigation pane. At the bottom of this screen, you will find the Access Management for Azure resources section.
Click the link Manage Security Default in this section and change the setting to Enable security defaults No.