Hi,
I recently bought both dlc's for the witcher Wild Hunt, but I have a very popular, as I noticed, problem. It's all about error: installation failed: disk access problem. That's what it says. And it's after the game is downloaded. It wouldn't have been much of a problem If I didn't pay a lot of money for them. There are many different ways around the Internet, how to overdrive the gog.com, but to be honest, I'm a newbie in that kind of things. I'm not much of a technician, so I'd please for a rookie-type answer, how can I install my dlc's so that they could work.
Best wishes
Customer

You could try copying your disc contents to hard drive and running setup from there. Label folders Disc 1, Disc 2 etc. You can delete these after.

I bought them via gog.com. I don't have any discs. I have read simewhere, that I could run a setup of a dlc manually, sowewhere in a game files, even though I bought a game through the Internet, but I have no clue where to look for it. There are some folders in the main folder of the game called dlc, and there are capacity-matching folders, but they only contain some unopenable, weirdly named stuff. Where to find such a installer?

To all who have that problem. Install the game from website gog.com. Worked for me