I've tried half a dozen times, it just doesn't work. During isntallation it get's to 100% and hangs there forever with a few MBs left, if I restart the Galaxy it just get's stuck on "allocating disk space" at 0%, if I try to import the folder it will get stuck around 28% forever. Is this because I'm using windows 10? Is there any known solution? Thank you

Yes, unfortunately Win 10 could be a source of the problem - or at least I encounter similar issues with Win10 and DLC installation.

While I can not guarantee that it will work in your case, this is what I've done:
1. Log off from Galaxy, turn off the Client completely
2. Scan and remove any windows-produced trash and leftovers from your system, especially from registry. If you know how to do it, you can do it manually or you can use software like CCleaner, BleachBit or something similar.
3. Make sure that you have enough disc space and it's not heavy fragmented
4. Launch Galaxy, log in again, try to install game

In my case it helps. Hope you will be lucky, too.

I'm on a clean install so the registry should be clean, I think the only option from the ones you listed is fragmented drive possibly.

Anyway I've tried to be patient this time and it went from 3.5MBs to 1MB in about an hour and finished in about another one, it's rather weird but I guess my issues are solved. Thanks for the help.