Dear Aspirant, in order to get compensatory time, you need to request the Chairman, JEE(Advanced) 2021, of the nearest Zonal Coordinating IIT in the prescribed format :- The requisition, along  with a copy of the PwD certificate(FORM-PWD [II/III/IV, whichever is applicable]) OR copy pf the certificates of Dyslexic candidate(FORM-DYSLEXIC 1 and DYSLEXIC 2), whichever is applicable, must be uploaded at the time of online registration for JEE(Advanced) 2021. I hope you are clear now. If you have any other doubts feel free to ask. All The Best!!!