curl --request POST \
  --url https://api.example.com/v2/signup/session \
  --header 'Content-Type: application/json' \
  --data '
{
  "business_name": "<string>",
  "user_email": "<string>",
  "callback_url": "<string>",
  "legal_entity_id": "<string>",
  "business_information": {
    "incorporation_region": "AL",
    "entity_type": "unset",
    "tax_classification": "unset",
    "llc_managed_type": "member_managed",
    "business_name": "<string>",
    "business_purpose": "<string>",
    "ein": "<string>",
    "incorporation_date": "2023-12-25",
    "naics_code": "<string>",
    "accounting_method": "accrual",
    "accounting_period": "fiscal",
    "accounting_year_end": 1,
    "futa_liability_year": "<string>"
  },
  "external_company_id": "<string>"
}
'

{
  "url": "<string>",
  "created_at": "<string>",
  "expires_at": "<string>",
  "legal_entity_id": "<string>"
}