South Africans, do you have to do a PCR test before coming over to the US? If so, how did you do it?

I live in the US and my mom is flying over this weekend from South Africa. She is fully vaccinated and has a negative test from receiving a booster shot last week. I have heard conflicting info about if that test is good enough to enter the US. If she has to do a PCR test, how do you do it?