In order to be able to claim the $300 ($600 for married filing joint) charitable deduction for non-itemizers you must have entered your charitable deductions under the Deductions and Credit screen under Donations to Charity 2021.

If you are still having difficulties or receiving an error message when you try to claim the $300 ($600 for married filing joint) as a non-itemizer on your 1040, below are instructions on how to fix that problem. The cause may be due to past state return donations being automatically transferred over to your current return. This will cause the donation amount on your return to not match with what you have listed in your return. If the amount transferred is less than the amount entered it may trigger the error message. Use the following steps to review your 2021 charitable contributions and add any additional donations.

Sign in and open any section of your return.
Search for donations and select the Jump To link in your search results.
Answer Yes to Did you make any donations to charity in 2021?
If you have an account with ItsDeductible Online, you can import your donations. If not, answer No and enter your donations manually on the next screen.
On the Review All Your Charities screen, make sure the total donation amount listed equals the total deductions entered for 2021.