Drop the .pak files into ORC\Content\Paks\~mods (create the ~mods folder).

The Ultimate Guide to Resident Evil: Operation Raccoon City FitGirl Repack

Resident Evil: Operation Raccoon City FitGirl Repack - A Comprehensive Guide

Because Operation Raccoon City is an older PC title originally designed for the defunct "Games for Windows Live" (GFWL) system, you might encounter some errors on modern Windows systems.

Right-click the game executable, go to Properties, navigate to the Compatibility tab, and check "Run this program as an administrator" and "Run in compatibility mode for Windows 7." If you want to optimize your setup further, let me know: What operating system are you running?