You don't need to explain why you did not receive the stimulus money.  You are able to claim the Recovery Rebate Credit on your 2020 return as long as for 2020 you are not a dependent of someone else.

After the Other Tax Situations section (Federal Review) of the 2020 TurboTax program you will be asked about the stimulus payment received or not received.

After you asked about the stimulus payment & you qualify, you will get the Recovery Rebate Credit (stimulus) on the 2020 federal tax return, Form 1040 Line 30.