I'm trying to download Galaxy, whenever i try to open the installer after downloading it, it just says "something went wrong, try downloading the installer again. If the problem persists, contact support"
downloaded a couple more times, same thing each time. I've never seen anything like this

Try an offline installer and see if you can install from that.
https://cdn.gog.com/open/galaxy/client/2.0.43.71/setup_galaxy_2.0.43.71.exe

From here

That worked, thank you so much :)