Adding a quixel material to my library doesn’t add it to the library…very bloody frustrating.
yes I can download it, but then have to extract it and save it to a folder, then import to UE, then make a material with the textures. Just wasting precious time!!
It used to be so easy, but oh no, lets just make our customers more frustrated than they normally are!
Do you mean library, or project?
Adding to the project is easy now with the fab plugin.
Edit: Ok, you mean library, right? 
I just tried that, and it also worked, although I don’t think it actually puts any files anywhere, it’s just a cookie operation.
My workaround is to go to https://www.fab.com/sellers/Quixel and copy the exact name of the Quixel asset. In Unreal, open the fab menu, paste the asset name in the generel search field. From there, it is possible to add it to the project.