Powershell Online script to start multiple workflows

# Add Wave16 references to SharePoint client assemblies and authenticate to Office 365 site - required for CSOM
Add-Type -Path (Resolve-Path "$env:CommonProgramFiles\Microsoft Shared\Web Server Extensions\16\ISAPI\Microsoft.SharePoint.Client.dll")
Add-Type -Path (Resolve-Path "$env:CommonProgramFiles\Microsoft Shared\Web Server Extensions\16\ISAPI\Microsoft.SharePoint.Client.Runtime.dll")
Add-Type -Path (Resolve-Path "$env:CommonProgramFiles\Microsoft Shared\Web Server Extensions\16\ISAPI\Microsoft.SharePoint.Client.WorkflowServices.dll")

# Specify tenant admin and site URL
$SiteUrl = "https://testlsharepoint.sharepoint.com/sites/developer/"
$ListName = "TestList"
$UserName = "kunnu@TestlSharePoint.onmicrosoft.com"
$SecurePassword = Read-Host -Prompt "Enter password" -AsSecureString

# Connect to site
$ClientContext = New-Object Microsoft.SharePoint.Client.ClientContext($SiteUrl)
$credentials = New-Object Microsoft.SharePoint.Client.SharePointOnlineCredentials($UserName, $SecurePassword)
$ClientContext.Credentials = $credentials
$ClientContext.ExecuteQuery()

# Get List and List Items
$List = $ClientContext.Web.Lists.GetByTitle($ListName)
$ListItems = $List.GetItems([Microsoft.SharePoint.Client.CamlQuery]::CreateAllItemsQuery())
$ClientContext.Load($List)
$ClientContext.Load($ListItems)
$ClientContext.ExecuteQuery()

# Retrieve WorkflowService related objects
$WorkflowServicesManager = New-Object Microsoft.SharePoint.Client.WorkflowServices.WorkflowServicesManager($ClientContext, $ClientContext.Web)
$WorkflowSubscriptionService = $WorkflowServicesManager.GetWorkflowSubscriptionService()
$WorkflowInstanceService = $WorkflowServicesManager.GetWorkflowInstanceService()
$ClientContext.Load($WorkflowServicesManager)
$ClientContext.Load($WorkflowSubscriptionService)
$ClientContext.Load($WorkflowInstanceService)
$ClientContext.ExecuteQuery()
# Get WorkflowAssociations with List
$WorkflowAssociations = $WorkflowSubscriptionService.EnumerateSubscriptionsByList($List.Id)
$ClientContext.Load($WorkflowAssociations)
$ClientContext.ExecuteQuery()

# Prepare Start Workflow Payload
$Dict = New-Object 'System.Collections.Generic.Dictionary[System.String,System.Object]'

# Loop List Items to Start Workflow
For ($j=0; $j -lt $ListItems.Count; $j++){
    $msg = [string]::Format("Starting workflow {0}, on ListItemId {1}", $WorkflowAssociations[0].Name, $ListItems[$j].Id)
    Write-Host $msg
    #Start Workflow on List Item
    $Action = $WorkflowInstanceService.StartWorkflowOnListItem($WorkflowAssociations[0], $ListItems[$j].Id, $Dict)
    $ClientContext.ExecuteQuery()
}