Yes, a person who is a dependent (but not actually claimed) can claim the American Opportunity Credit.

Does your software have another spot that asks if they actually WERE claimed?  I suspect that may be what you need to look for.

However, the dependent (but not actually claimed) can usually only claim the non-refundable portion (to offset income tax, if they have any).  In most cases, they won't qualify for the refundable portion (see link).

https://www.irs.gov/publications/p970#en_US_2024_publink1000211799