I've been attempting to acquire a digital backup of my years-old retail copy of The Witcher, specifically the Platinum Edition

First, I entered the CD Key into gog.com/witcher/backup only to be told "This code doesn't look like one of ours. Please check that you entered the code correctly. Some characters, like 0 & O, or 1, I & l, can look similar in print." Tried all the common possible substitutions, I instead of l et cetera, but nothing.

Then I tried thewitcher.com/en/backup, followed the instructions given but whenever I hit send it just loads for ages and ages then I get this:

Error 503 Service Unavailable

Service Unavailable

Guru Meditation:

XID: 1441485105

Varnish cache server

So, what's the next step if there is any?

Waiting worked, the site came back online. Thanks.

I'm having the same problem as Zoomy had,
I've tried to enter the CD Key on the gog.com/witcher/backup site but it just says that the code wasn't found. I've also tried it with the GOG Galaxy 2.0 launcher but it just says "the code doesn't look like one of ours. etc"
I've tried the thewitcher.com/en/backup site but apperntly the site doesn't offer that service any more.
I don't really know what more to do, does anyone of you maybe know of a way to solve this?