You have to access your own account and/or print it for yourself using exactly the same account and user ID that you used when you prepared the return.
Many people have multiple TT accounts and forget how to access them. Log out of the account you are in now.
Account recovery
What did you download? The pdf file or the .tax2020 file? Any device should open a pdf file. If you downloaded the data file ending in .tax2020 you need a full Windows or Mac computer to install the Desktop CD/Download program to open a .tax file.
The TurboTax tax data file which has a file extension of .taxyyyy, where yyyy is the tax year of the file such as .tax2020 for tax year 2020, can only be opened by the TurboTax software for the year of the file. The TurboTax software can only be installed on a personal computer, desktop or laptop, Windows or Mac, not on a mobile device.
The PDF of the tax return can be opened by any PDF compatible application, such as Adobe Reader.
How to save the tax return as a PDF using the TurboTax mobile app - https://ttlc.intuit.com/community/saving/help/how-do-i-save-my-return-as-a-pdf-in-the-mobile-app/01/26812
How to print your tax return using the TurboTax mobile app - https://ttlc.intuit.com/community/printing/help/how-do-i-print-my-return-in-the-mobile-app/01/27034