You want users logging into their account in the Fivetran dashboard to provide a second factor of authentication (e.g. code via SMS).
Fivetran does not support two-factor authentication (TFA) when logging in with a native Fivetran account.
However, many identity providers (e.g. Okta and Azure Active Directory) provide two-factor authentication as a standard capability. You can configure Fivetran to authenticate your users via these external identity providers using SAML.
Use the Fivetran setup guide to configure authentication with SAML.
SAML authentication provides the added benefit of being able to control access to Fivetran from within your own identity management system.