Worldpay belongs underneath event commerce rather than inside the planner workflow. Large venues, attractions, ticketing companies, and event platforms may need its acquiring scale, APIs, fraud controls, and multi-currency reach.
Most event organizers should start elsewhere. If you just need to sell tickets or collect registration fees, a ticketing platform, Stripe, Square, or PayPal will usually be easier to price, launch, and support. Worldpay becomes relevant when payment operations are big enough to justify enterprise complexity.