Sorry---you cannot use desktop download software on an iPad. If you still need to prepare a 2021 return you need a full PC or Mac in order to use TurboTax. IPads, phones, etc. do not meet the system requirements for the desktop software. Do you have access to a full PC or Mac?
You might need to go to a local tax place or if you have a simple return and 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
You have to print and mail prior year returns. When you mail a tax return, you need to attach any documents showing tax withheld, such as your W-2’s or any 1099’s. Use a mailing service that will track it, such as UPS or certified mail so you will know the IRS received the return. Don’t forget state.
Important! Mail Federal and State in separate envelopes and mail each year in separate envelopes.
And....are you behind on 2022 and 2023 as well? If so, you will have the same issue, since online software is only for 2024. If you are behind on 2021, 2022 and 2023, you will not be able to use TT unless you can use a full PC or Mac. There may be other software from TT's competitors that you can use, but I do not know which ones.