Workflow subscription service does not return any value - sharepoint-2013

Question

I am trying to start the SharePoint 2013 workflow thru the powershell csom model. I have browsed and got many links with the same promising coding. But in my case it is not working. I have tried both in on premises sharepoint 2013 and sharepoint online but none them worked out. Below is the code:
Set-ExecutionPolicy Unrestricted
Add-Type -Path "C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\16\ISAPI\Microsoft.SharePoint.Client.dll"
Add-Type -Path "C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\16\ISAPI\Microsoft.SharePoint.Client.Runtime.dll"
Add-Type -Path "C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\16\ISAPI\Microsoft.SharePoint.Client.WorkflowServices.dll"
# Specify tenant admin and site URL
$SiteUrl = "https://spoffice365.sharepoint.com/"
$ListName = "Test"
$UserName = "myusername"
$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()
}
The below $WorkflowAssociations does not return any value both in sharepoint 2013 and sharepoint online always comes as empty, even though the $List.Id passed correctly and verified that list has approver workflow configured.
$WorkflowAssociations = $WorkflowSubscriptionService.EnumerateSubscriptionsByList($List.Id)
$ClientContext.Load($WorkflowAssociations)
$ClientContext.ExecuteQuery()
And also would like to learn how to pass approver name to the below method:
$WorkflowInstanceService.StartWorkflowOnListItem($WorkflowAssociations[0], $ListItems[$j].Id, $Dict)