Extract the .zip contents (using tools like 7-Zip) directly into the main Resident Evil 4 installation folder.
For those looking for the save locations instead of the classic edition, they are typically found in your Steam userdata folder under ID 2050650 . File: Resident Evil 4 - Ultimate HD.zip ...
If you are attempting to use a .zip file for modding or installation, common community steps from guides on Steam include: Extract the
Always back up your bin32 and bio4\etc folders before modifying files. File: Resident Evil 4 - Ultimate HD.zip ...
When prompted, select "Overwrite" to apply the new HD textures or patches.