The "Unable to find layout.properties file" error during R12.8.x install occurs from a common oversight when performing a stand-alone installation.
Release: R12.8 Any
Component: WAMUI
The prerequisite and UI installers need to be in the same directory so that it can find the layout.properties and Framework.
The downloads are separate so it is natural that they would be unzipped into separate folders. If the prerequisite and UI installer are located in separate directories you will see the "Unable to find layout.properties file" error.
Consolidating the extracted files into the same folder will correct the error.
The documentation does make a note about this:
Installation Prerequisites