My daughter was born on April 10, 2020 and I have not been able to add her on as a dependent. It states “that date does not look correct”. How do I add her?

You are completing your 2019 tax return, and therefore it will not accept a date of birth of 2020. You will not add your child to your 2019 return. CRA will have your information and know you have a baby. When you complete your 2020 tax return then you will add your child.