Hello the samples downloaded with the build does not work

I get the error Fatal error: Uncaught PDOException: could not find driver in C:\wamp64\www\koolreport\datasources\PdoDataSource.php on line 57

Urgent help required for connecting using PDO to postgresql connection

my config file has the following:

<?php return array( __ "postdb"=>array(

    "connectionString"=>"pgsql:host=127.0.0.1;port=5432;dbname=xyz",
    "username"=>"postgres",
    "password"=>"543",__
),

);

Urgent assistance required