Hi aspirant,

According to the criteria set up for participating in CSAB counseling those candidates who participate in JoSAA 2021 but failed to get allotted will be eligible for CSAB special round 2021 or Candidates who were allotted through JoSAA 2021 but failed to confirm their admission or withdrew from their seats will also be eligible for CSAB 2021 special round.

since you have been successfully allotted seat seat and you have even accepted it by paying the fee so you cannot participate in CSAB counseling until you withdraw your candidature in jossa counselling.

To know more about CSAB counseling 2021, visit https://engineering.careers360.com/articles/csab

Hope it helps!!