The wikipedia article suggests doubt on the Archimedes connection - https://en.wikipedia.org/wiki/Antikythera_mechanism

In particular when it says "it was demonstrated in 2017 that the calendar on the Metonic Spiral is indeed of the Corinthian type but cannot be that of Syracuse," although as evidence goes that doesn't sound definitive.

Nevertheless, it is important to remember that Archimedes was part of an active intellectual community and is reported to have written a (now lost) manuscript on the construction of planetarium-style models ("On Sphere-Making"), so whether or not the artifact is directly from Archimedes there might be an intellectual link.