How to display custom payment methods in Woocommerce with shipping disabled?

Question

WordPress

In the online store, the calculation of delivery is disabled, since the delivery will be carried out by a third-party company. I included a custom payment option in the instructions but they don't show up at checkout. Tried different plugins but nothing works. As I understand it, it depends on whether the calculation of delivery is included or not? Who can tell me how to enable custom payment without delivery.