1. Switch on cfggameplay.json
DayZ only reads starter kits through cfggameplay.json, and only reads that file when enableCfgGameplayFile is on. In your Nitrado server settings, make sure it's switched on. If it isn't, nothing in this guide will apply.
2. Build the kit
A kit is a small JSON file that lists what goes in each clothing slot, what's carried, how worn each item is and which items get hotbar keys. Put several items in a slot and DayZ picks one at random, so spawns don't all look the same.
The free Blxckforge Starter Kits editor builds the file on a loadout board, so you never hand-write the JSON. You can run several kits side by side and set how often each one is used.
3. Upload the kit and list it
Upload the kit to your mission folder (a custom folder keeps things tidy), then add its path to spawnGearPresetFiles under PlayerData in cfggameplay.json. Restart the server.
On the Server and Pro plans, Save to server does both steps for you, shows every change first and backs up anything it replaces.