We believe you have disabled the 2-factor authentication for sub-users. Please login to your SVR account with the root admin account and go to Settings > Account > Security Policy and uncheck the Disable two-factor authentication for sub-users option. The users can further log in with their respective accounts and check the status of 2-factor authentication from their user profile.
Apologies for that. Unfortunately, we don't have 2FA for SVM. Please feel free to log it as an enhancement via your Flexera support Community Ideas page.