Hello aspirant, 

Well to get a seat in CSAB Special Round you have to first be JEE Main qualified. Now as per the 2019 JEE Main cutoff , for ST category the cutoff is 44.33 percentile. Now as per your rank of 16980, you may get a good seat in CSAB Special Round but for that you have to attend the CSAB counselling. CSAB counselling will begin after the completion of JoSAA. Now exactly which college and what seat will you get that is hard to tell. So better attend the counselling process for CSAB and see which colleges are you getting. Through this particular counselling, you can get a seat in NITs,IIITs,GFTIs. 

You can go through this link and checkout the details regarding CSAB Special Round : https://engineering.careers360.com/articles/csab

Good Luck !!!!