IISER will release portal and document for uploading of the marksheet details. SO you have nothing to worry about. You should wait patiently for some time and keep an eye on the official website of IISER Aptitude Test. The notification is likely to be out after the examination.

To know more about IISER Aptitude test visit the link below:

https://engineering.careers360.com/exams/iiser-aptitude-test

I hope this answer helps. All the very best for your future endeavors!