curl --request POST \
  --url https://api.kajabi.com/v1/forms/{id}/submit \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/vnd.api+json' \
  --data '{
  "data": {
    "type": "<string>",
    "attributes": {
      "name": "<string>",
      "email": "<string>",
      "phone_number": "<string>",
      "business_number": "<string>",
      "address_line_1": "<string>",
      "address_line_2": "<string>",
      "address_city": "<string>",
      "address_state": "<string>",
      "address_country": "<string>",
      "address_zip": "<string>",
      "custom_1": "<string>",
      "custom_2": "<string>",
      "custom_3": "<string>"
    }
  }
}'

{
  "data": {
    "id": "<string>",
    "type": "<string>",
    "attributes": {
      "name": "<string>",
      "email": "<string>",
      "phone_number": "<string>",
      "business_number": "<string>",
      "address_line_1": "<string>",
      "address_line_2": "<string>",
      "address_city": "<string>",
      "address_state": "<string>",
      "address_country": "<string>",
      "address_zip": "<string>",
      "custom_1": "<string>",
      "custom_2": "<string>",
      "custom_3": "<string>"
    },
    "relationships": {
      "site": {
        "data": {
          "id": "<string>",
          "type": "<string>"
        }
      },
      "form": {
        "data": {
          "id": "<string>",
          "type": "<string>"
        }
      }
    }
  },
  "links": {
    "self": "<string>",
    "current": "<string>"
  }
}