Yes you have to enter what you already got to see if you qualify for any more. And if you don't enter it then Turbo Tax will give it to you again on your tax return.
When you go through the federal review tab it will ask how much you got if any. Or to enter your stimulus payment in TurboTax, type "stimulus" (without the quotes) in the Search box, then click the link that says "Jump to stimulus." Say no to the amounts it shows you. Then 2 boxes will open up for each round. If you didn't get one enter a 0 in the box.
After you have entered your tax information and are ready for the Federal Review, it will be the first question.
If you are trying to trigger it, you can go to Other Situations, answer any questions and click Done. The next automatic selection is Federal Review and it will ask about payments received.
The Recovery rebate credit is on 1040 line 30. It either adds to your refund or reduces a tax due.
If you are not being prompted to enter them then you probably don't qualify based on your 2020 return or you are being claimed as a dependent.
A 1040 is the tax return form you prepare here to send to the IRS. If you start entering data in this software you are preparing a Form 1040. Please look at it so you will know what you are sending to the IRS:
Click on Tax Tools on the left side of the screen. Click on Tools. Click on View Tax Summary. Click on Preview my 1040 on the left side of the screen.