Tell us about your dependents page of Turbo Tax. My children are adults: I do not know their income. How do I proceed past this page without an error stopping me

If your children are adults then they are no longer "dependants", therefore you do not claim them as "dependants" on your tax return. They would file their own tax returns.

Footnote: We at TurboTax want to encourage you and your close family to take all necessary precautions to ensure your safety. Please review the articles provided below for more information during these difficult times: 

• Tax Deadlines & Benefits Changes: A Response to COVID-19 for Individuals & Small Business 
• Canada Emergency Response Benefit (CERB) 
• Apply for Canada Emergency Response Benefit (CERB) with CRA