500 Internal Server Error on https://copyleaks.com/api/v3/education/submit/ocr/my-custom-id

Question

I wanted to scan a free text only(images not included) from copyleaks and they offer me this documentation https://api.copyleaks.com/documentation/v3/education/submit/ocr but I'm getting the 500 Internal Server Error using this Request body(raw json type)

{
  "base64": "dGhlIHF1aWNrIGJyb3duIGZveA==",
  "filename": "image.jpg",
  "langCode": "en",
  "properties": {
    "webhooks": {
      "status": "https://{yoursite.com}/webhook/{STATUS}/my-custom-id"
    }
  }
}

Note: {yoursite.com} was replaced with my actual url

I was able to get a 200 response from this request https://id.copyleaks.com/v3/account/login/api using this request body(raw json type)

{
    "email": "***",
    "key": "****"
}

Can someone help me with my problem?