Spring Boot Freemarker will not display html page

I have a Spring Boot application in which I need to use Freemarker to display HTML pages in a browser.

I am new to Freemarker and I am struggling to display even a simple HTML page, and I do not know why it will not display the page.

My template file is in src/main/resources/templates, and my freemarker config is:

 @Bean
  public FreeMarkerConfigurer freeMarkerConfigurer() throws IOException, TemplateException {
    FreeMarkerConfigurer freeMarkerConfigurer = new FreeMarkerConfigurer();
    freeMarkerConfigurer.setTemplateLoaderPath("classpath:/templates");
    freeMarkerConfigurer.setDefaultEncoding("UTF-8");
    freemarker.template.Configuration configuration = freeMarkerConfigurer.createConfiguration();
    configuration.setTagSyntax(freemarker.template.Configuration.SQUARE_BRACKET_TAG_SYNTAX);
    configuration.setRecognizeStandardFileExtensions(true);
    configuration.setOutputFormat(HTMLOutputFormat.INSTANCE);
    freeMarkerConfigurer.setConfiguration(configuration);

    return freeMarkerConfigurer;
  }

  @Bean
  public ViewResolver viewResolver() {
    FreeMarkerViewResolver viewResolver = new FreeMarkerViewResolver();
    viewResolver.setCache(false);
    viewResolver.setPrefix("");
    viewResolver.setSuffix(".ftlh");
    viewResolver.setContentType("text/html; charset=utf-8");
    return viewResolver;
  }

And my controller is:

@RestController
public class HelloWorldController {

    @GetMapping("/hello-world")
    public String helloWorld(@ModelAttribute("model") ModelMap model) {
        String message = "Hello World!";
        model.addAttribute("message", message);
        return "hello";
    }
}

I am using ftlh file extension for templates and my hello.ftlh file looks like:

[#import "_components.ftlh" as comp]

[@comp.page title="Hello"]
    [@comp.hello]${message}[/@comp.hello]
[/@comp.page]

Replace @RestController with @Controller. @Controller is meant for rendering views and allows returning view names that resolve to templates