If you're looking for a free version, consider:
Can someone explain what risks I'm taking by pirating movies?
: Sells the "Édition 2 DVD" in French and bilingual widescreen versions. Local Second-Hand Stores
: Provide options to rent or buy the movie digitally, typically including the French dub. Physical Media (DVD/Blu-ray)
If you're interested in the series, consider exploring legal options to enjoy "Harry Potter à l'école des sorciers" and other titles in the franchise. Enjoy the wizarding world!