If you have submitted the options of EWS and EBC category during your form fill up then you will be required to submit the certificate during counselling or as instructed by the organizer. Now if you have not selected the EWS option, then you have nothing to do and you can't submit the certificate.

The eligibility for the EWS certificate are:

• The annual income of the family of candidate should not exceed 8lakh per annum.
• The family should not hold 5 or more than 5 acres of land.
• The family shouldn't have a residential area more than 1000 sq feet.
• The family shouldn't have a residential plot (in notified municipalities) of an area 100 square yards or more.
• The family shouldn't have residential plot (other than in notified municipalities) of area 200 square yards or more.

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