As title suggests. I've tried many times over a long period to get the Galaxy client to take but I cannot get it to accept the code for one reason or another. Any suggestions?

You no longer require a code. Just download it.

The code is no longer necessary. Download it from here.

Will Galaxy be available for Windows XP at some point? Or is it working for XP ATM just not officially supported?

It's apparently working, but it's not officially supported. At least, not yet.

i download it and it still ask for a code

Can you be more specific as to what requires a code?

Why would they bother officially supporting XP? Windows XP is unsupported by Microsoft and as such does not receive any more updates which makes it really dangerous to use on any PC connected to the Internet. Nobody should encourage people to do such a thing by supporting software on that ancient operating system.

It ask me that i am not connect to the galaxy client and there is a button where it's writen: connect, so when i click on it it redirect my page to a place where i need to do a redeem code

Obviously you're talking about The Witcher, which isn't connected to your GoG account I guess. You need to put your The Witcher retail key there, which you may find in the box with the game.

That message shows up when Galaxy has detected a GOG game that isn't available in your account.

Let me make a guess; have you installed Witcher 3 from a retail disc and want to buy the expansions? Before you can do that, you must first redeem the GOG code that should be available in the back of the manual.

No, me its for Dying Light

Where did you buy the game?
Can you see it in your library?

Yes, its there, its on the page og the game when i click on it in my library that it ask to connect myself

Honestly, I have no clue what is happening to you. I can only suggest contacting GoG support