get https://www.signwell.com/api/v1/bulk_sends/csv_template
Fetches a CSV template that corresponds to the provided document template IDs. CSV templates are blank CSV files that have columns containing required and optional data that can be sent when creating a bulk send. Fields can be referenced by the field label. Example: [placeholder name]_[field label] could be something like customer_address or signer_company_name (if "Customer" and "Signer" were placeholder names for templates set up in SignWell).