The TurboTax online editions for tax year 2021 are closed. Only tax year 2022 is available using the online editions.
To complete and file a 2021 tax return using TurboTax you would need to purchase, download and install on a personal computer, Windows or Mac, one of the 2021 desktop editions from this website - https://turbotax.intuit.com/personal-taxes/past-years-products/
A 2021 tax return cannot be e-filed using TurboTax, it can only be printed and mailed.