curl --request POST \
  --url https://qubesync.com/api/v1/connections/{connection_id}/onboarding_url \
  --header 'Authorization: Basic <encoded-value>' \
  --header 'Content-Type: application/json' \
  --data '{
  "redirect_url": "https://myapp.com/quickbooks-setup-callback"
}'

{
  "data": {
    "id": "123e4567-e89b-12d3-a456-426614174000",
    "last_connected_at": "2023-01-01T12:00:00Z",
    "name": "My Customer Inc.",
    "app_id": "550e8400-e29b-41d4-a716-446655440000",
    "company_file": "My Company File.QBW",
    "username": "550e8400-e29b-41d4-a716-446655440001",
    "qbxml_version": "14.0",
    "quickbooks_product_name": "QuickBooks Pro 2021",
    "type": "standard",
    "redirect_url": "https://myapp.com/quickbooks-setup-callback",
    "links": {
      "self": "/api/v1/connections/123e4567-e89b-12d3-a456-426614174000",
      "ui": "/app/connections/123e4567-e89b-12d3-a456-426614174000",
      "onboarding": "https://qubesync.com/onboarding/123e4567-e89b-12d3-a456-426614174000"
    }
  }
}