You are too late to use online TurboTax for a 2021 tax return. The only way to use TurboTax now for 2021 is to purchase the CD/download and use it on a full PC or Mac. You cannot use it on a mobile device of any sort. And the return cannot be e-filed; it can only be filed by mail now. You have to print it, sign it in ink and mail it in.
Or you might still be able to use the software on the IRS Free File site.
Use this IRS site for other ways to file for free. There are 8 free software versions available from the IRS Free File site
https://apps.irs.gov/app/freeFile/
To do a prior year return you have to buy the Desktop program here,
https://turbotax.intuit.com/personal-taxes/past-years-products
You will need a full Windows or Mac to install it on.
If you want to file for free you can fill out the forms by hand. Here are some basic forms…..
Here is the IRS 2021 Form 1040
https://www.irs.gov/pub/irs-prior/f1040--2021.pdf
or if you want bigger type use 1040SR for Seniors,
https://www.irs.gov/pub/irs-prior/f1040s--2021.pdf
And 2021 Instructions
https://www.irs.gov/pub/irs-prior/i1040gi--2021.pdf
2021 Tax and EIC Tables
https://www.irs.gov/pub/irs-prior/i1040tt--2021.pdf
Sch 1 : https://www.irs.gov/pub/irs-prior/f1040s1--2021.pdf
Sch 2 : https://www.irs.gov/pub/irs-prior/f1040s2--2021.pdf
Sch 3 : https://www.irs.gov/pub/irs-prior/f1040s3--2021.pdf
