Hello Aspirant...

IISER admissions in 2021 will be done through three channels: JEE Advanced, KVPY, and the IISER aptitude test. Candidates applying through Jee Advanced must have a general category rank of less than 15000 and a category rank of less than 10000. Candidates who apply through the IISER aptitude test or the KVPY must meet the IISER cutoff marks. You must be taking admission based on your JEE Advanced rating, since you specified it. With your current rank, you will almost certainly be admitted to IISER.

I hope this information is useful.

All the best.