Export-PowerBIDataflow

Here is my PowerShell script:

$credential = New-Object -TypeName System.Management.Automation.PSCredential -ArgumentList "APPID", ("Secret" | ConvertTo-SecureString -AsPlainText -Force)

Connect-PowerBIServiceAccount -ServicePrincipal -Tenant "TenantID" -Credential $credential -Environment "Public"


Export-PowerBIDataflow -WorkspaceId "eae420bb-eb1b-40a5-90d6-a057156bdcc6" -Id "459dc124-187d-48cf-9888-4f2be43f61bf" -OutFile C:\Users\chbonier\Documents\DTF

Here is the error :

Export-PowerBIDataflow : Failed to write dataflow with ID 459dc124-187d-48cf-9888-4f2be43f61bf to file C:\Users\chbonier\Documents\DTF. Message: L'accès au chemin 
d'accès 'C:\Users\chbonier\Documents\DTF' est refusé.
Au caractère Ligne:6 : 1
+ Export-PowerBIDataflow -WorkspaceId "eae420bb-eb1b-40a5-90d6-a057156b ...
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : WriteError: (Microsoft.Power...PowerBIDataflow:ExportPowerBIDataflow) [Export-PowerBIDataflow], Exception
    + FullyQualifiedErrorId : Failed to write dataflow with ID 459dc124-187d-48cf-9888-4f2be43f61bf to file C:\Users\chbonier\Documents\DTF. Message: L'accès au chemin  
   d'accès 'C:\Users\chbonier\Documents\DTF' est refusé.,Microsoft.PowerBI.Commands.Data.ExportPowerBIDataflow

Why access to the path is refused ?

Thanks In Advance, 

Charline