Yes...You must enter that 1099-R form. IF you don't have it, log in to you 401k account access and download it as a PDF, or contact them to get a copy.
The tax withholding done was only a "required" amount...it could have been overwithholding...or it may not have been enough. Your tax return that you are preparing will be the final accounting for taxes for ALL your income for all of 2020. When you enter that 1099-R in the software, you will also be entering the tax withholding already done, and it will be credited against all your potential taxes for the year.
SO yes...you need to have and enter all income forms, including both W-2 and 1099-R forms.
____________*Answers are correct to the best of my knowledge when posted, but should not be considered to be legal or official tax advice.*