I want to create a resource group and after that create NSG in same resource group.

ARM template –

{
  "$schema": "http://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
  "contentVersion": "1.0.0.0",
 "resources": [
    {
      "type": "Microsoft.Resources/deployments",
      "apiVersion": "2021-04-01",
      "name": "deployment-rg",
      "location": "easatus",
      "subscriptionId": "[parameters('subscriptionId')]",
      "properties": {
        "mode": "Incremental",
        "template": {
          "$schema": "https://schema.management.azure.com/schemas/2018-05-01/subscriptionDeploymentTemplate.json#",
          "contentVersion": "1.0.0.0",
          "resources": [
            {
              "type": "Microsoft.Resources/resourceGroups",
              "apiVersion": "2021-04-01",
              "name": "demo-test",
              "location": "eastus",
              "properties": {}
            }
          ],
          "outputs": {}
        }
      }
    },
    {
      "type": "Microsoft.Resources/deployments",
      "apiVersion": "2021-04-01",
      "name": "deployment-nsg",
      "comments": "test vnet",
      "resourceGroup": "demo-test",
      "dependsOn": [
        "['deployment-rg']"
      ],
      "properties": {
        "mode": "Incremental",
        "template": {
          "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
          "contentVersion": "1.0.0.0",
          "resources": [
            {
              "apiVersion": "2020-05-01",
              "type": "Microsoft.Network/networkSecurityGroups",
              "name": "nsg",
              "location": "eastus",
              "properties": {
                "securityRules": [
                  {
                    "name": "AllowAll",
                    "properties": {
                      "priority": 100,
                      "protocol": "*",
                      "sourcePortRange": "*",
                      "destinationPortRange": "4489",
                      "sourceAddressPrefix": "Gateway",
                      "destinationAddressPrefix": "*",
                      "access": "Allow",
                      "direction": "Inbound",
                      "sourcePortRanges": [],
                      "destinationPortRanges": [],
                      "sourceAddressPrefixes": [],
                      "destinationAddressPrefixes": [],
                      "description": "more info."
                    }
                  }                  
                ]
              },
              "tags": {
                "resourceType": "Demo NSG",
                "clusterName": "Apps Demo"
              }
            }
          ]
        }
      }
    }
  ]
}

I have used depends on as well in NSG still getting below error –

Error: Code=ResourceGroupNotFound; Message=Resource group
‘demo-test’ could not be found.

Any idea what is wrong here.