Receiving Past Stimulus Checks

Hello. I am extremely new to all of this. I filed my taxes for the first time for the 2020 year. I got my refund already. Now I am eligible for the 3rd Stimulus, I got that part. What I am not understanding is that on the IRS website there is something called the 2020 Recovery Rebate Credit. I am not sure what that is, what I need to do to get it or if I am even eligible for it. I didn't file my taxes for 2019, my parents did that. So I'm not sure what to do. Someone please help.