curl --request POST \
  --url https://{defaultHost}/v1/{app_id}/users \
  --header 'Authorization: Bearer <token>'

{
  "user": {
    "id": "usr_1234567890",
    "app_id": "<string>",
    "user_id": "<string>",
    "email": "user@example.com",
    "phone": "+1234567890",
    "created_at": "2023-11-07T05:31:56Z",
    "updated_at": "2023-11-07T05:31:56Z",
    "user_meta": {
      "first_name": "John",
      "last_name": "Doe",
      "custom_field": "value"
    }
  },
  "user_meta_errors": {}
}