You can treat this as a normal sale of non-employee stock in TurboTax.
If the income and taxes were reported properly on your 2020 W-2 from the stocks and cash you received, you do not need to indicate that those stocks were RSUs now that you are selling them in 2021. The cost basis should be their value when you acquired them in 2020, which it sounds like it is. The holding period will be determined based on whether you held them longer than a year. If so, they qualify for long-term capital gains treatment.
