Need help setting up postfixadmin with a Postfix mail server?

Question

postfix

postfixadmin setup gives error
Postfix Admin Setup Checker
Running software:

PHP version 7.0.33-0+deb9u3+b1
Apache/2.4.25 (AstraLinuxCE)
Checking for dependencies:

Magic Quotes: Disabled - OK
Depends on: presence config.inc.php - OK
Checking $CONF['configured'] - OK
Error: Smarty template compile directory templates_c is not writable.
Please make it writable.
If you are using SELinux or AppArmor, you might need to adjust their setup to allow write access.
Depends on: MySQL 4.1 - OK
(change the database_type to 'mysqli' in config.inc.php if you want to use MySQL)
Error: Can't connect to database
Please edit the $CONF['database_*'] parameters in config.inc.php.
DEBUG INFORMATION:
MySQL 3.x / 4.0 functions not available! (php5-mysql installed?)
database_type = 'mysql' in config.inc.php, are you using a different database?

Depends on: session - OK
Depends on: pcre - OK
Depends on: multibyte string - OK
Depends on: IMAP functions - OK
Please fix the errors listed above.