Whenever I try to use GOG downloader all the options except settings are blanked out. For some reason GOG galaxy cant install. I'm stuck, and really want to play the Witcher 3, please help.

Have you tried this?
Install GOG Downloader Login and Install The Witcher 3 from this link

if you use the downloader you need to go to the game image in your account, click on it and search in the options for the gog downloader links. You just need to click the links it gaves you. I hope this helps :)

Thanks, GOG downloader links worked :D

And you can always download your files via browser, no other software needed. Log in to your account, goto the game page in your library, and click on each file for them to download et voila!

I solved it