Hey!There

There are three channel with which you can take admission in IISERs

KVPY: Candidates are offered admission on the basis of valid KVPY FELLOWSHIP

SCB(State and central board channel):To get admission through this channel candidate have to qualify aptitude test

Joint entrance examination of Indian institute of technology: Candidate with valid jee advance score card can take admission..

For more details visit below mention link:

https://www.google.com/url?sa=t&source=web&rct=j&url=https://engineering.careers360.com/articles/iiser-admission/amp&ved=2ahUKEwjh7L7N6ZHkAhVK4nMBHeqvC9kQFjAEegQIDBAK&usg=AOvVaw2gB1J2q-opG38-6LYjmUn0&ampcf=1.

GOOD LUCK!