If you not upload nativity certificate before application last date then maybe you still can upload if correction window open, some exams like KEAM allow to upload documents like nativity late during correction time, not all certs accepted late but nativity usually possible if you miss, but after correction window close then no chance, if you already submit and lock form then you need call helpline or write mail to exam board, they tell if allow or not, so you always check correction date carefully and upload fast before it close.

See full detail about document upload and nativity info in this link

https://engineering.careers360.com/articles/document-required-for-keam-registration