How to use NinjaRMM to run an application via API?

I have a script like this listed on the device:

{
      "type": "SCRIPT",
      "id": 67,
      "name": "script.run_application",
      "language": "native",
      "architecture": [
        "64",
        "32"
      ],
      "categoryId": 3
},

I assume I can run msiexec/cmd via an API, so did a request like this:

curl --request POST 
  --url https://app.ninjarmm.com/v2/device/228/script/run 
  --header 'Accept: */*' 
  --header 'Authorization: Bearer <mytoken>' 
  --header 'Content-Type: application/json' 
  --data '{
  "type": "SCRIPT",
  "id": 67,
  "parameters": "C:\Windows\System32\cmd.exe",
  "runAs": "NT AUTHORITY\SYSTEM"
}'

But I get an error:

{ "resultCode": "FAILURE", "errorMessage": "NullPointerException", "incidentId": "WEB_MGMT_SERVICE-<some long letter>" }

I assume I messed up the parameters? Can someone explain how to correctly use this script via API?