If you qualify but didn't file your 2021 return, you need to file it to claim the third payment/ Recovery Rebate Credit by the April 15, 2025, deadline.
Please check Here to file your 2021 return.
Stimulus payments from 2020 are no longer available.
If you were not claimed as a dependent on a 2021 tax return, you should have received the 2021 stimulus of $1,400.
Go to this IRS website for a tax account and check to see if the IRS sent you the stimulus payment - https://www.irs.gov/payments/online-account-for-individuals
If not, then you either have to file a 2021 amended return or if you never filed a 2021 return then you have to file a 2021 return or an amended return on or before April 15, 2025.
You complete the Recovery Rebate section of the 2021 return.
See this TurboTax support FAQ for amending a prior year tax return - https://ttlc.intuit.com/turbotax-support/en-us/help-article/tax-return/amend-change-correct-return-already-filed/L4VjJ9BA2_US_en_US?uid=ld1n99kr
To complete and file a 2021 tax return using TurboTax you would need to purchase, download and install on a personal computer one of the 2021 desktop editions from this website - https://turbotax.intuit.com/personal-taxes/past-years-products/
A 2021 tax return can only be printed and mailed, it cannot be e-filed using TurboTax.