2. Get the Inno Setup script plus related files by cloning the whole [monero-core GitHub repository](https://github.com/monero-project/monero-core); you will only need the files in the installer directory `installers\windows` however
3. The setup script is written to take the GUI wallet files from a subdirectory named `bin`; so create `installers\windows\bin`, get the zip file of the GUI wallet from [here](https://getmonero.org/downloads/), unpack it somewhere, and copy all the files and subdirectories in the `monero-gui-0.12.3.0` directory to this `bin` subdirectory