Zkoss Hello World example 404 not found error

Question

I'm very new to this Zkoss framework and web developing The problem I'm facing is that when I run the "index.zul" file on my Apache Tomcat server, it always result in a 404 error despite following every tutorial I found. The details of the error is:

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HTTP Status 404 – Not Found Status Report Type

message The requested resource [/test2/index.zul] is not available

description The requested resource is not available.

Apache Tomcat/10.1.9

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I'm using zk studio version 9.6.0.1, Apache Tomcat version 10.1.9 This is what appears in the console:

SEVERE: Error configuring application listener of class [org.zkoss.zk.ui.http.HttpSessionListener]
java.lang.NoClassDefFoundError: javax/servlet/ServletRequestAttributeListener
    at java.base/java.lang.ClassLoader.defineClass1(Native Method)
    at java.base/java.lang.ClassLoader.defineClass(ClassLoader.java:1012)
    at java.base/java.security.SecureClassLoader.defineClass(SecureClassLoader.java:150)
    at org.apache.catalina.loader.WebappClassLoaderBase.findClassInternal(WebappClassLoaderBase.java:2487)
    at org.apache.catalina.loader.WebappClassLoaderBase.findClass(WebappClassLoaderBase.java:865)
    at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1401)
    at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1245)
    at org.apache.catalina.core.DefaultInstanceManager.loadClass(DefaultInstanceManager.java:490)
    at org.apache.catalina.core.DefaultInstanceManager.loadClassMaybePrivileged(DefaultInstanceManager.java:472)
    at org.apache.catalina.core.DefaultInstanceManager.newInstance(DefaultInstanceManager.java:142)
    at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4381)
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:4892)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1332)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1322)
    at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
    at org.apache.tomcat.util.threads.InlineExecutorService.execute(InlineExecutorService.java:75)
    at java.base/java.util.concurrent.AbstractExecutorService.submit(AbstractExecutorService.java:145)
    at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:871)
    at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:846)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1332)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1322)
    at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
    at org.apache.tomcat.util.threads.InlineExecutorService.execute(InlineExecutorService.java:75)
    at java.base/java.util.concurrent.AbstractExecutorService.submit(AbstractExecutorService.java:145)
    at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:871)
    at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:241)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
    at org.apache.catalina.core.StandardService.startInternal(StandardService.java:428)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
    at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:910)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
    at org.apache.catalina.startup.Catalina.start(Catalina.java:795)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.base/java.lang.reflect.Method.invoke(Method.java:568)
    at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:347)
    at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:478)
Caused by: java.lang.ClassNotFoundException: javax.servlet.ServletRequestAttributeListener
    at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1437)
    at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1245)
    ... 40 more

I appreciate you all!