I have just installed the game (TW3 WH) after trying an illegit one. It is so amazing so I bought the game. My problem is that I can't save the progress. There is no manual or autosave. The permission of the documents folder has been set to all. The game works perfectly, but I just can't save it. What did I miss? I downloaded the game from gog.com.

Hi.
After reading this,
https://www.gog.com/forum/the_witcher_3_wild_hunt/faq
and if it does not help you solve your issue,
I suggest finding the folder where the game saves are located and disabling the 'Read Only' seting, on its propeties tab.

I have the same issue , it seems to have to do with windows 10 and the savegames folder.

-I ran the game as admin
-gave permission to everyone , only me , only admin .
-disabling read only on the savegames folder
-reinstalling the game

Nothing seems to work so any help is appreciated .

I feel you guys.
Windows 10 updates have messed up a lot of gamers. What I suggest is try removing Windows 10 updates one by one, untill you see your issue resolved, followed by uninstalling and reinstalling the game.
https://www.wikihow.com/Uninstall-All-Windows-Updates
What I propose though, is reverting to your previous OS, if you upgraded, because Windows 10 are currently the worst choice for gamers, due to compatibility/performance issues on many, but not all, titles.