Hello Preethi, first of all congratulations to you for getting such a good rank in SRMJEE PG. With 621 rank chances of getting admission in M.Tech CSE branch in Kattankulathur campus is not so high. If you were lucky enough at the time of counselling then you will fetch a seat in main campus otherwise you have to compromise by taking into other campus. But all the campus have same ranking and it will not affect much.

Hope this helps.

All the best!!

Hai!  Your score is better. Since you are applying for PG you should got above 50% to 60% mark in your UG program. 

Better you can apply for admission. Best of luck.