I graduated with a BS on 5/20. I started at community college in ‘15 and transferred to university ‘17. My parent have claimed AOTC in 16,17,18,19. Can I claim ATOC ‘20?

No. Your parents used up your four times. After answering all the questions (including how may times the AOTC was used), TurboTax will qualify you for either the Lifetime Learning Credit or the Tuition and Fees Deduction.