You should have uploaded the declaration in support of your category. However a notice from JEE Advanced authority had been announced that said,

" Due to COVID-19 related restrictions hindering the issuance of various certificates in time, valid category certificate(s) may be uploaded at the time of reporting after seat allocation. Accordingly, certificate upload portal will be enabled for document upload at the time of reporting after seat allocation. For details of seat allocation schedule, visit JoSAA website (https://josaa.nic.in/) "

Visit https://jeeadv.ac.in/ and check the notice of 25th September. So, there is no need to worry about uploading the certificates.

All the best.