Asus has probably removed this software suit from Driver & Tools for the time being.
From the SABERTOOTH Z77 "FAQ" page -
https://www.asus.com/us/support/FAQ/1035296
[Motherboard] AI suite 3 can't properly work
Last Update : 2018/01/23 18:25
Microsoft newly released “Windows security updates” compilers used by ASUS AI SUITE 3 are experiencing conflicts.
Due to Microsoft newly released Windows security updates compilers used by ASUS software are experiencing conflicts and causing some issues with ASUS software, such as Ai suite 3;
This version is currently under review, ASUS will release a completed and verified software version for users to download at a later date.