{
  "$schema": "https://schema.management.azure.com/schemas/2015-01-01/deploymentParameters.json#",
  "contentVersion": "1.0.0.0",
  "parameters": {
    "appPrefix": {
      "value": "GEN-UNIQUE"
    },
    "adminUsername": {
      "value": "GEN-UNIQUE"
    },
    "vmsize": {
      "value": "Standard_A1"
    },
    "existingAtlasInfraName": {
      "value": "GEN-UNIQUE"
    },
    "existingAtlasToken": {
      "value": "GEN-UNIQUE"
    },
    "adminPasswordOrKey": {
      "value": "GEN-SSH-PUB-KEY"
    }
  }
}

{
  "$schema": "https://schema.management.azure.com/schemas/2015-01-01/deploymentParameters.json#",
  "contentVersion": "1.0.0.0",
  "parameters": {
    "appPrefix": {
      "value": "GEN-UNIQUE-10"
    },
    "adminUsername": {
      "value": "GEN-UNIQUE"
    },
    "vmsize": {
      "value": "Standard_A1"
    },
    "existingAtlasInfraName": {
      "value": "GEN-UNIQUE"
    },
    "existingAtlasToken": {
      "value": "GEN-UNIQUE"
    },
    "adminPasswordOrKey": {
      "value": "GEN-SSH-PUB-KEY"
    }
  }
}

Add char limit for GEN-UNIQUE value for appPrefix parameter
Add char limit for GEN-UNIQUE value for appPrefix parameter
