Access Denied When Using WindowsIdentity.RunImpersonated for File Operations

Question

I am trying to perform file operations (upload, download, delete) in a user's file system using impersonation in C#. After researching, I came across the WindowsIdentity.RunImpersonated method, which I’m using to delegate authority for file operations.

However, I am encountering an Access Denied error. Below is the relevant code I have implemented:

public class ImpersonationManager
{
    private SafeAccessTokenHandle _safeAccessTokenHandle;

    private readonly string _domainName;
    private readonly string _userName;
    private readonly string _password;

    [DllImport("advapi32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
    public static extern bool LogonUser(String lpszUsername, String lpszDomain, String lpszPassword,
   int dwLogonType, int dwLogonProvider, out SafeAccessTokenHandle phToken);

    public ImpersonationManager(string domainName, string userName, string password)
    {
        _domainName = domainName;
        _userName = userName;   
        _password = password;
    }   

    public SafeAccessTokenHandle GetSafeAccessTokenHandle()
    {

        const int LOGON32_PROVIDER_DEFAULT = 0;
        const int LOGON32_LOGON_INTERACTIVE = 2;
        try
        {
            bool returnValue = LogonUser(_userName, _domainName, _password,
                               LOGON32_PROVIDER_DEFAULT, LOGON32_LOGON_INTERACTIVE,
                               out _safeAccessTokenHandle);

            if (!returnValue)
            {
                int ret = Marshal.GetLastWin32Error();
                throw new System.ComponentModel.Win32Exception(ret, $"LogonUser failed with error code : {ret}");
            }
        }
        catch (Exception ex)
        {
            throw;            
        }    

        return _safeAccessTokenHandle;
    }

}

public async Task<bool> UploadFileAsync(string filePath = null, File file = null, Stream fileStream = null)
{
    if (file == null)
        throw new ArgumentNullException(nameof(file));

    if (fileStream == null)
        throw new ArgumentNullException(nameof(fileStream));

    SafeAccessTokenHandle safeAccessTokenHandle = GetSafeAccessTokenHandleAsync();

    WindowsIdentity.RunImpersonated(safeAccessTokenHandle,() =>
    {
        var fileName = file.FileName;

        try
        {
            using (FileStream destinationStream = new FileStream(filePath, FileMode.Create, FileAccess.Write, FileShare.None))
            {
                fileStream.CopyTo(destinationStream);
                return true;
            }
           
        }
        catch (Exception ex)
        {
            throw;
        }

    });

    return true;

}