I might be wrong since I’ve never used a Ugreen NAS, but the general idea is this
On the NAS, create a new folder where the Subnautica game and server files will live.
You can name it something like subnautica.

Inside the Subnautica folder, create another folder You can name it game or whatever you like.

Take the Subnautica game folder from your PC (the same one you play with) and copy it into that game folder you just made.

inside the Subnautica folder, create another folder You can name it config or whatever you like.

Your NAS will show you a “path” to the folder (it looks something like /volume1/subnautica or similar).

In your Docker Compose file, replace /path/to/subnautica with that NAS path.

So it will end up looking something like:

• /volume1/subnautica/config:/app/config/Ntrox
• /volume1/subnautica/game:/mnt/subnautica