As someone mentioned, if you relocated the library but then restored the system, the link is obviously lost. Logic was reverted to before the library was relocated so expects it to be in its original location, which is not, so it tries to download again.
You can stop the download, or install just the essential sounds if not possible to stop and then simply copy each library folder back to overwrite the current minimal library. When started, Logic will detect that they are installed, it simply checks for the existence of sounds, there is not an installation file that needs to be there.
Alternatively, you can leave it where it is, or organise it in any way you want (as long as you keep the original file and folder names: "Apple Loops", "Alchemy Samples", "EXS24 Samples" etc), delete corresponding folders in the original location and put symbolic links (not aliases) instead. This is what I've done and I freed up a tone of space on the main drive, just the programs there, and the big libraries on external SSD/HDD. Logic will see them just fine and even install updates in the correct location on the external drive.
Hope this helps.
