Tried the online installer yesterday night on a Windows 7 64bit laptop and it appears the installer is putting the pak files in the wrong location.
Here's the steps I took:
1 - Run the installer as Administrator;
2 - The installer asks you where to put the game files. Place them in "C:\Program Files (x86)", the installer will add the "Simutrans" folder for you;
3 - Choose the paks you want. In my case I choosed only Pak128;
4 - Let the installer do it's work, it will download the game files and then the pak files;
5 - Confirm that the game files are in "C:\Program Files (x86)\Simutrans", as expected;
6 - Check that the pak files are not there but they are actually directly under the "C:\Program Files (x86)" folder. In my case it was "C:\Program Files (x86)\pak128".
If you run the game's executable file (simutrans.exe) it will say there's no pak installed and will prompt you to choose a pak to install but the pak will still be installed on "C:\Program Files (x86)\pak128" instead of "C:\Program Files (x86)\Simutrans\pak128".
If you cut & paste the "pak128" folder into the right location everything works fine.
I guess the part of the installer that installs the pak files is forgeting to add the Simutrans folder to the path.
That is an "error" of pak128 which break the old convention that the paks are always in a folder "Simutrans". The installer can handle such paks, but aparently I did not enable this feature.
I will upload a corrected pak128