Learn Italian: Maria si è dovuta scusare per il ritardo. - Maria had to apologize for the delay.

When a modal verb like dovere (to have to) is followed by a reflexive verb like scusarsi (to apologize), the choice of auxiliary depends on where you put the reflexive pronoun (si). Because si is placed before the conjugated verb, you must use essere.

Why does dovuta end in -a instead of the usual -o?

Whenever you use essere as the auxiliary in the passato prossimo, the past participle must agree with the subject. Since Maria is a single female, the participle changes from dovuto to dovuta.

Is there a way to say this exact same sentence using avere?

Yes! You can attach the reflexive pronoun directly to the end of the infinitive verb. If you do that, the auxiliary switches to avere and the past participle does not change its ending: Maria ha dovuto scusarsi per il ritardo. Both versions are perfectly natural and mean the same thing.

How does scusare mean apologize here?