This is on the 1040/1040SR Worksheet. Why is Turbotax requiring me to add a non-zero value to line 10b "Charitable contributions if you take the standard deduction"?

If you did not make any charitable contributions in 2020, delete any entry you inputted on this screen (even if you entered $0). For this year, even if you don’t itemize, you may take a charitable deduction of up to $300 for cash contributions made in 2020 to qualified organizations.

You will also have to make sure you filled out the charitable contributions section correct in TurboTax. 

Please follow these steps: 

1. Open your return.
2. Search charitable contributions with the magnifying glass tool at the top of the page. 
3. Click the Jump to charitable contributions link.
4. If you made no donations to charity, answer no. 
5. Continue your return.