Below are the default save file locations by platform:
Ubisoft Connect PC
Steam
PlayStation 4
Xbox One
Nintendo Switch
Ubisoft Connect PC
C:\Program Files (x86)\Ubisoft\Ubisoft Game Launcher\savegame\<UbisoftConnectID>\5183
Please note that Assassin's Creed Liberation saves are stored in a separate folder:
C:\Program Files (x86)\Ubisoft\Ubisoft Game Launcher\savegame\<UbisoftConnectID>\3600
Steam
C:\Users\%user%\Documents\Assassin's Creed III Remaster\Saves
PlayStation 4
Settings > Application Saved Data Management > Saved Data in System Storage > Assassin's Creed III Remastered
Xbox One
My Games and Apps > Assassin's Creed III Remastered > Menu > Manage Game > Saved Data
Nintendo Switch
System Settings > Data Management > Save Data/Screenshots
If you have any questions, feel free to contact us!