You need to make sure the PowerShell has write permission to the folder you're trying to write to.  You can do this by

1. Relaunching Powershell as Administrator
2. Specifying a folder that PS can write to *without* elevated permissions
  * Try `C:\temp\` (plus your `filename.csv`)
  * Or call [`Path.GetTempPath`][1] in PS with `[System.IO.Path]::GetTempPath()`

**See Also**: [Export-Csv - Access to the path 'C:\export.csv' is denied][2]

[1]: https://learn.microsoft.com/en-us/dotnet/api/system.io.path.gettemppath
[2]: https://stackoverflow.com/q/60611518/1366033

I'm trying to get the permission of the calendar folder on a set user, then export it to a CSV, so we can easily view the permissions.

When I run this command:

```cs
Get-Mailbox |
    Get-MailboxPermission |
    Select-Object AccessRights, User, Identity, IsValid |
    Export-Csv -Path 'c:\Users\Connor\Desktop'
```

I get this error:

```none
Export-Csv : Access to the path 'C:\Users\Connor\Desktop' is denied.
At line:1 char:89
+ ... hts,User,Identity,IsValid | Export-Csv -Path 'c:\Users\Connor\Desktop'
+                                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : OpenError: (:) [Export-Csv], UnauthorizedAccessException
    + FullyQualifiedErrorId : FileOpenFailure,Microsoft.PowerShell.Commands.ExportCsvCommand
```