1. set $CONF['configured'] = true; and also enter the database details in config.inc.php file in manual installation
2. PHP REQUIREMENT LINK : requirement display on setup page of installation (check composer.json as well).
3. Release date : https://github.com/postfixadmin/postfixadmin/releases/
4. Kept PHP requirement as 7.4 as mentioned by vendor (https://github.com/postfixadmin/postfixadmin/issues/879)