Gold Edition Uses nativePC_MT, Normal Resident Evil 5 Uses nativePC
You Can install them without Fluffy Manager but for modding RE5 add the mod's .ARC Archive file to:
1. For Gold Edition: Resident Evil 5 Gold Edition\nativePC_MT\Image\Archive
2. For Normal Resident Evil 5: Resident Evil 5\nativePC\Image\Archive
Also, Set your RE5 Folder is Fluffy's Manager and There's two ways for adding RE5 Folder and the two ways' completely simple!
First Way: Open Fluffy's Manager, Head to Settings, Choose Set Resident Evil 5, Write Your RE5 Folder
Example: C:\Program Files\Steam\SteamApps\Common\Resident Evil 5 - Gold Edition
Second Way: Open Config.CFG using WordPad at:
Fluffy's Manager 5000\Data\Config.CFG and find line modman_re5_dir and after : you'll find space, add your RE5 Folder after the blank space
Hope it Helps