I would pick CCW when procurement owns contingent labor and the company already buys, approves and pays suppliers in Coupa. In that setup, agency temps and SOW projects become one more spend category under the same approval rules, supplier records and invoice controls as the rest of indirect spend.
It is a weaker choice for HR-led programs. A Workday HCM customer who wants contractors in the same record as employees will get closer with Workday VNDLY, and a recruiting team wanting talent pools and redeployment will find Avature or SimplifyVMS more developed on direct sourcing.
Coupa does not sell MSP services, so as with VNDLY you either run the program internally or hire an MSP to operate CCW for you.
The DCR heritage matters when judging maturity. Smart Track VMS was already a full contingent workforce and services procurement product before Coupa bought it, covering sourcing, work orders, onboarding controls, time and expense, deliverable sign-off and invoicing, so CCW was not built from scratch inside a procurement suite. What Coupa added is the surrounding platform: supplier management, approvals and payments shared with the rest of indirect spend.