Add existing content type to list using Powershell csom

Need to add Add existing content type directly to SPO list using Powershell : this the code :

    function Add-ContentType($loginUsername,$password,$url,$listTitle,$contentTypeID)
{

   $ctx=New-Object Microsoft.SharePoint.Client.ClientContext($url)
   $ctx.Credentials = New-Object Microsoft.SharePoint.Client.SharePointOnlineCredentials($loginUsername, $password) 
   $ctx.Load($ctx.Web.Lists) 
   $ctx.ExecuteQuery()


  $contentType=$ctx.Web.ContentTypes.GetById($contentTypeID)
  $ctx.Load($contentType)

 $ll=$ctx.Web.Lists.GetByTitle($listTitle)
 $ctx.load($ll)
 $ctx.load($ll.ContentTypes)
 $ctx.ExecuteQuery()
  $ll.ContentTypesEnabled=$true
 $addedContentType=$ll.ContentTypes.AddExistingContentType($contentType)
 $ll.Update()
  try
     {

         $ctx.ExecuteQuery()
         Write-Host "Adding content type " $addedContentType.Name " to " $ll.Title
     }
     catch [Net.WebException]
     {
        Write-Host $_.Exception.ToString()
     }



}

the $ctx have:

Web                          : Microsoft.SharePoint.Client.Web
Site                         : Microsoft.SharePoint.Client.Site
RequestResources             : Microsoft.SharePoint.Client.RequestResources
FormDigestHandlingEnabled    : True
ServerVersion                : 16.0...
Url                          : https://Site/sites/aaa
ApplicationName              : .NET Library
ClientTag                    : 
DisableReturnValueCache      : False
ValidateOnClient             : True
AuthenticationMode           : Default
FormsAuthenticationLoginInfo : 
Credentials                  : Microsoft.SharePoint.Client.SharePointOnlineCredentials
WebRequestExecutorFactory    : Microsoft.SharePoint.Client.DefaultWebRequestExecutorFactory
PendingRequest               : Microsoft.SharePoint.Client.ClientRequest
HasPendingRequest            : True
Tag                          : 
RequestTimeout               : 180000
StaticObjects                : {[Microsoft$SharePoint$SPContext$Current, Microsoft.SharePoint.Client.RequestContext]}
ServerSchemaVersion          : 15.0.0.0
ServerLibraryVersion         : 16.0...
RequestSchemaVersion         : 15.0.0.0
TraceCorrelationId           : 0a4dc19d-c084-3000-c314-44a6737157a6

the problem is :

$ctx.Web.Lists =is empty 

$ctx.Web.Lists.GetByTitle($listTitle) empty also.

any idea .