like r/AssassinsCreed and r/AC3 have pinned threads and community spreadsheets dedicated to save sharing. Search for "AC3 save file exchange" or "Sequence 6 save request" to find active discussions. Users often share personal saves they've uploaded to Google Drive or Dropbox.
The first five sequences of the game force you to play through hours of Haytham Kenway’s prologue and Connor's childhood. Downloading a Sequence 6 save lets you jump straight into the core Assassin gameplay. Assassin 39-s Creed 3 Sequence 6 Save File Download