Hi Ulisse,{I had originally given up trying to install the patch.} I finally worked out how to get that 4GB patch to work, I found out how to go about it by reading a reply in the Steam Forums by one of your Moderators.
So now I have it installed and all is well.
I have had lots of patches and installations over the many years, most with Train Simulator and there have been many different ways of doing them.
Some were rather tricky, then some wizz would work out a simple way to install the whole thing with one simple installation program they wrote.