It's very simple, you don't need to install IKEA Chairs Collection library:

instruction:

1 - unpack the zip file.

2 - in your library create a folder "IKEA CHAIRS_COLLECTION" and copy the files inside.

3 - open Blender: edit/preferences/file paths/add path to asset library, select the folder  and you can find all assets in "asset browser panel". 

enjoy!

if you have any questions do not hesitate to write us!