I found the icon pack I'm trying to select here: https://www.opendesktop.org/p/1012430.
I extracted the folder and copied it to
However, the icon pack is not listed in Icons menu. I tried restarting GNOME Tweaks, re-downloading the icon pack but nothing worked. I'm sure there's nothing wrong with the pack itself since I tried using other packs and they didn't work too.
I'm using Ubuntu 19.04.