How to export private key from ePass3003 usb token in C#?

I have a USB sign token that it is contains public key and private key with RSA Encryption Algorithm, I could export public key file with command

> openssl x509 -pubkey -noout -in mystamp.cer > pubkey.txt

Now I need to export private key this public key from token USB in c#.
Also I use this code

X509Store store = new X509Store(StoreName.My, StoreLocation.CurrentUser);

        store.Open(OpenFlags.ReadOnly);

        X509Certificate2 cert = store.Certificates.Find(X509FindType.FindByThumbprint, "71faaced4d4ae3d81399faa61fbc13c56bce0638", false)[0];

        // Export the certificate including the private key.
        byte[] certBytes = cert.Export(X509ContentType.Pkcs12, "My Password Of Token");
        
        var privateKey = (System.Security.Cryptography.RSACryptoServiceProvider)cert.PrivateKey;
        var privateKeyString1= privateKey.ToXmlString(false);// I when change to true get an error
        var privateKeyString2= Convert.ToBase64String(certBytes);

But when privateKeyString1 or privateKeyString2 pass to this method CryptoUtils.SignData()
I get an error for private key format.

You cannot export the private key from your token (which is actually a smart card. That's the main purpose of hardware security modules tokens (or smart cards) that key material cannot leave the hardware. However, this doesn't prevent you from using the key for signing or encryption operations by calling middleware APIs.