fenrir2112: it was chrome and browser the first time then downloader
Try this using Internet Explorer instead of Chrome
1- Go to your shelf, click on The Witcher cover and set the "GOG download mode" to OFF.
2- Click on the link that says "Game installer part 1 of 6". When the dialog box comes up choose the option "Save" and save that file to a folder in your PC.
3- Repeat step 2 for the other 5 parts of the game installer. You need all 6 parts of the installer ( 1 .exe file and 5 .bin files) saved in the same folder on your PC in order to be able to install the game
The download for the game is big, around 8,5 GB's, so it will take you a while to download all the required files, but how much time it will take depends of how fast your connection is.