Just as my topic says when I go to the page for claiming that game (on the Witcher hub page) and press that "claim" button, it takes me to the Galaxy page.

Ok, I installed it and back again. Pressing "claim" it takes me again to main Galaxy page for downloading... Wtf???

Afterwards, I tried from the program/app with the same result. Galaxy was opened, signed in and it still takes me to the downloading page.

I will upload some images, one of it is the app opened and running and the next shows that it takes me to the download Galaxy page.
Oh, I was gonna forget - the PC is running Windows 10 (64-bit), Processor - Inter Xeon E5420 (2.50 GHz) with 4 GB Ram.

I hope someone can help me out here because I am puzzled a lot..... :-\

Anyway, thanks a lot in advance and happy New year to all as well! :-)

There's supposed to be a banner in the Recent category. I don't know if that's what you're looking at in the screenshot, since I'd already bought the game by the time it was made available for free. See if the following post helps. There's a second method to obtain the game in there as well.
https://www.gog.com/forum/general_beta_gog_galaxy_2.0/game_giveaway/post2

If the problems persist, the community giveaway had 6 copies of the game available last time I checked. You normally need forum activity to be eligible, but you could try asking for an exception to be made since the game is permanently free.
https://www.gog.com/forum/general/the_community_giveaway_gog_edition_redux/page1

it could be banned in his country or he has his account set to be under 18 years of age... both break the bullshit script Gog uses

contact support is my advice... its their job