How do I get a long snow path with water?
What long snow path?
Oh a moat and draw bridge? What decent castle doesn’t have a draw bridge? Lol
For unlocking a longer maximum length for the path (the thing on the ground that connects attacker’s tent with defender’s castle gate), you have to upgrade your castle gate. Then you can change your path to be longer.
Concerning moats, those are currently not part of the game.
Concerning snow, when selecting the castle gate, there’s a button for changing the environment of your base, and one available option is a snow landscape.
If none of the above is the answer to your question, please rephrase your question to make it more understandable.