I have this problem, but the library it's on my ext folder.

I changed the php.ini file adding the driver.
The php_pdo_firebird.dll is only an interface between PHP and the firebird engine. So you need firebird installed and also the php-pdo-firebird.dll needs to be able to find fbclient.dll
Try copying fbclient.dll into \wamp\bin\php\php7.1.10
If you also need access from Apache you may need to copy fbclient.dll into \wamp\bin\apache\apache{version}\bin as well and also amend the php.ini file that controls PHP under apache. Do that by using the wampmanager menus to edit the correct php.ini file like this
left click wampmanager icon -> PHP -> php.ini