Magento 2.4.0 come with Two-Factor authentication. Once you installed Magento 2.4.0 or latest you will be asked to setup Two-Factor Autentication.
To Disable Two-Factor Authentication, edit file
'Magento_TwoFactorAuth' => 1,
'Magento_TwoFactorAuth' => 0,
php bin/magento setup:upgrade
php bin/magento setup:static-content:deploy -f
Now you will be able to login to Magento Admin with out setting up Two-Factor autentication.