PHP unable to load dynamic library "php_pdo_oci.dll"

The ..._oci.dll is part of the Oracle C Interface. Unless you need to use Oracle, I suggest you go to the relevant line inside the php.ini file and uncomment the loading of this extension. However, if you need to use this extension, you’ll need to install the free Oracle Client libraries and add them to the path.

Oracle has an article Installing PHP and the Oracle Instant Client for Linux and Windows on how to do this.