If changes don't appear in-game:
From that point on, whenever you run the server, the cfggameplay.json will be loaded and used by the game. dayz json files install
Installing and managing DayZ JSON files is a fundamental skill for modern server administration. From gameplay tweaks in cfggameplay.json to custom structures through object spawners, JSON files give you unprecedented control over your server's behavior. If changes don't appear in-game: From that point
Here are some popular JSON files for DayZ: whenever you run the server
If you're trying to that comes as a .json file only — that's not possible. JSON is just config data, not the mod itself. You still need the .pbo files in @ModName\addons\ .