Most likely, you downloaded the final PDF. That will include all calculation forms and worksheets. Depending on the types and sources of income you had in 2020, I would expect no more than the first 15 pages should be needed.
Basically, you need the base 1040 form (2 pages) and any of the schedules printed. For example, SCH C if you had self-employment income, SCH E if you had rental income, SCH F if you had farming income, etc. There's also the numbered schedules 1 thru 6. Any of those that you have should be included also.
