How to enable PostgreSQL driver for PDO for php 7?

You've been running php7.1 while you installed php7.0 pgsql module.

Try php -v to check your version and install php7.1-pgsql.

Also you need to uncomment these lines:

extension=php_pdo_pgsql.dll
extension=php_pgsql.dll

in /etc/php/7.1/cli/php.ini .