Hi Pradeep!! For getting admission in IIT Madras for aerospace engineering,you have to appear for JEE MAINS and clear the cut-off marks assigned to your category for the given year to appear for JEE Advanced then you need to appear for JEE Advanced and clear the cut-off of IIT-M for aerospace engineering and you also should have 75% marks in your class 12 board exams.If you want further details on cut-off of IIT-M you can refer to this link : https://engineering.careers360.com/articles/jee-advanced-cutoff-for-iit-madras 

Hope this helped.Thank you.