Both careerindianairforce.cdac.in and afcat.cdac.in are official websites of IAF AFCAT. When you go to careerindianairforce.cdac.in, you get two options: Join as Officer, and Join as Airman. If you click on Officer, then you reach https://afcat.cdac.in/AFCAT/, and if you click on Airman, then you reach https://airmenselection.cdac.in/CASB/.
At the former, you can click on CANDIDATE LOGIN >> AFCAT 02/2019 - CYCLE to reach your login page for AFCAT 2/2019.