They primarily want forms attached to the return that show income tax withheld. Below are the official instructions. If your 1099's don't show any income tax withheld, you do not need to attach them.
From the form 1040 instructions
Assemble Your Return
Assemble any schedules and forms behind Form 1040 in order of the “Attachment Sequence No.” shown in the upper right corner of the schedule or form. If you have supporting statements, arrange them in the same order as the schedules or forms they support and attach them last. Do not attach correspondence or other items unless required to do so. Attach Forms W-2 and 2439 to the front of Form 1040. If you received a Form W-2c (a corrected Form W-2), attach your original Forms W-2 and any Forms W-2c. Attach Forms W-2G and 1099-R to the front of Form 1040 if tax was withheld.
Hope that helps.
I do not have the free version but I assume all versions have the same information. There should be a page preceding the first page of each of your federal and state tax returns. It starts off with "File by Mail Instructions for your 2020..." and has a red circle containing a white check mark in the right upper corner. Scan down the left side of the page where there is a category titled "What You Need to Mail." That will tell you to return your tax return and any additional attachments. My federal filing instructions say to include my W-2. You will also need to send the tax return and any forms that are generated by Turbo Tax as part of your return. You can find them by clicking on the button "Print/Save for your Records" and then click on Print. The popup window that opens will give you options of what to print. Select "All official forms required for filing."