The most legitimate source would be the publisher's website. Many publishers provide digital resources for teachers and sometimes for students, which can include corrigés.
(Relationships and social life) L’actu en direct (Current events and media) Consommer autrement (Consumption and environment) On part en voyage ? (Travel and exploration) On recrute (Work and professional life) L’appel de la nature (Nature and environment) edito a2 corriges pdf
Teachers can use corrigés to prepare lessons, correct student exercises more efficiently, and provide immediate feedback. The most legitimate source would be the publisher's website