curl --request POST \
  --url https://api.hubapi.com/crm/v4/associations/{fromObjectType}/{toObjectType}/batch/associate/default \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '{
  "inputs": [
    {
      "from": {
        "id": "<string>"
      },
      "to": {
        "id": "<string>"
      }
    }
  ]
}'

{
  "completedAt": "2023-11-07T05:31:56Z",
  "numErrors": 123,
  "requestedAt": "2023-11-07T05:31:56Z",
  "startedAt": "2023-11-07T05:31:56Z",
  "links": {},
  "results": [
    {
      "associationSpec": {
        "associationCategory": "HUBSPOT_DEFINED",
        "associationTypeId": 279
      },
      "from": {
        "id": "<string>"
      },
      "to": {
        "id": "<string>"
      }
    }
  ],
  "errors": [
    {
      "subCategory": {},
      "context": {},
      "links": {},
      "id": "<string>",
      "category": "<string>",
      "message": "<string>",
      "errors": [
        {
          "subCategory": "<string>",
          "code": "<string>",
          "in": "<string>",
          "context": "{\"missingScopes\":[\"scope1\",\"scope2\"]}",
          "message": "<string>"
        }
      ],
      "status": "<string>"
    }
  ],
  "status": "PENDING"
}