How do I record losses for 2021 if there were no losses recorded in the prior year 2020?

If you had losses that you were not previously allowed due to the passive activity rules, and they did not carry over, then you may have to enter them manually.  To enter any carryforward of passive losses for your rental follow the steps below.

You will need the Form 8582 from your 2020 tax return for the carryover amount to be included in your income as a loss on Schedule E. The image below will show you the entry screens from TurboTax online which will be similar to the CD/Download version.

If they were not entered on your 2020 return, you may need to amend that return for them to be on record for 2021.  However you can continue the 2021 return currently and amend later.