You can unzip it anywhere.
It is probably a good idea to create a folder where you place all your downloaded content.
After you saved it and unzipped it into this folder, you will have to either load the object itself or the folder containing it as a Library. This is done in the Library Manager Dialog.
Loving Archicad since 1995 - Find Archicad Tips at x.com/laszlonagy
AMD Ryzen9 5900X CPU, 64 GB RAM 3600 MHz, Nvidia GTX 1060 6GB, 500 GB NVMe SSD
2x28" (2560x1440), Windows 10 PRO ENG, Ac20-Ac27