Elle ne l'apprécia pas au premier abord.

English Translation

She didn’t like him at first.

Apprecia? Is it correct?

Hello @GambaCloze, welcome!

“Apprécia” is indeed correct here. This tense is called “passé simple”. It is similar to the preterit or simple past but it is not used nearly as much. You will see it in books and in formal documents, but you won’t hear it too often in everyday conversations. When speaking, people often use the “passé composé” instead, to refer to past events.