curl --request POST \
  --url https://app.tryordinal.com/api/v1/subscribers \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "postId": "550e8400-e29b-41d4-a716-446655440000",
  "userIds": [
    "550e8400-e29b-41d4-a716-446655440011",
    "550e8400-e29b-41d4-a716-446655440012"
  ]
}
'

{
  "createdSubscribers": [
    {
      "id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
      "user": {
        "id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
        "firstName": "<string>",
        "lastName": "<string>"
      },
      "createdBy": {
        "id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
        "firstName": "<string>",
        "lastName": "<string>"
      },
      "createdAt": "2023-11-07T05:31:56Z"
    }
  ],
  "existingSubscribers": [
    {
      "id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
      "user": {
        "id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
        "firstName": "<string>",
        "lastName": "<string>"
      },
      "createdBy": {
        "id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
        "firstName": "<string>",
        "lastName": "<string>"
      },
      "createdAt": "2023-11-07T05:31:56Z"
    }
  ]
}