La Spezia Bus Station to the Train Station

According to Google Maps, the Flixbus stop is 3.6 km from La Spezia Centrale rail station. Try to confirm that location with them, since it's not the same place that Google first identified as the "bus station" (on Piazza Chiodo). For a local bus connection, expect to buy bus tickets at a TI, tobacco shop, bar, or newsstand. Either way, this is probably another reason to opt for a train from Siena.