Context Path for my Spring Boot REST API

I already deployed my Spring Boot API into fly.io with hostname https://spring-boot-rest-api-postgresql.fly.dev

My API should be {IP}/api/books but it saying that 404.

What Can I do for that?

Repo Link: GitHub - hendisantika/spring-boot-rest-api-postgresql: Plain RESTful Web Service with Spring Boot. Using PostgreSQL database, Hibernate and basic authentication.

Thanks