I used GOG Downloader to download the game. A small GOG.com Downloader window appeared. It did not download, just Pause Windows Installer, English _ Paused.
The Resume All / Pause All buttons on top are grayed out.
There is the new Patch, and I manage to download it using the GOG Downloader just fine.
Please Help.

Thanx

Have you already tried rebooting your computer?

Alternatively, there are always the direct download links. Browse to your game shelf, open the gamecard for GK 20th anniversary edition and use the switch to turn the downloader off. Now click the links to download the files directly.

Thank you very much
i turn off the downloader, and download the files directly. it took a while , but I did manage to play the game right now.

You're welcome. It's good, GOG is offering both ways, the downloader and the direct links, because under certain circumstances one is usually better than the other and if one doesn't work there's alway a plan B.