Trying to install it from Galaxy. Goes to 2% then stops with "Installation failed (E3) Failed to connect to GOG.com servers." Retried about 10 times. Always the same.

Same here. Servers must be crashing out from too many people trying to download. Knew I should have bought on Steam smh.

EDIT: It seems things were even worse on Steam during launch. I apologize to the nation of Poland for my outburst.

same problem

Yep same here, i think we broke gog servers, too many people? hehehe, oh well whats another couple of hours after waiting so long for the game.
On a side note devs have localized the prices, i think, at least here in Brazil im paying 10 dollars for it, 60 reais, great job devs.

Same problem here. As a workaround, you can dowload offline installer from the website.

Don't think, it is a bandwidth issue.
The offline installer just downloads fine. But I want to play it with galaxy...

Can it be installed manually and then integrated into Galaxy later?

its work now! skong time!

Yeah, works now!

Yep mine went through too, just installed.