TYPO3: Can't find the Ajax Route

Question

I did that Tutorial from the TYPO3 Page v11.5:

https://docs.typo3.org/m/typo3/reference-coreapi/11.5/en-us/ApiOverview/Backend/Ajax.html

First of all my Extention Tree:

├── Classes
│   └── Controller
│       └── ExampleController.php
├── Configuration
│   ├── Backend
│   │   └── AjaxRoutes.php
│   └── Services.yaml
├── Resources
│   ├── Private
│   │   └── Templates
│   │       └── test.html
│   └── Public
│       └── JavaScript
│           └── Calculate.js
├── composer.json
├── ext_emconf.php
└── ext_localconf.php

My AjaxRoutes:

<?php
use (privacy)\ajaxcool\Controller\ExampleController;

return [
    'myextension_example_dosomething' => [
        'path' => '/ajaxcool/do-something',
        'target' => ExampleController::class . '::doSomethingAction',
    ],
];

My ext_localconf.php

<?php

$GLOBALS['TYPO3_CONF_VARS']['FE']['ajaxRoutes']['myextension_example_dosomething'] = [
    'path' => '/ajaxcool/do-something',
    'target' =>
(privacy)\ajaxcool\Controller\ExampleController::class . '::doSomethingAction',
];

In the bottom of this TYPO3 Tutorial Page is a JS Tutorial there i get an Error because i cant use require in the frontend. So i thought i can use fetch so i wrote that Script:

const baseUrl = 'https://ajax-typo3-test3.ddev.site/';
const inputNumber = 5;
fetch(`${baseUrl}/ajaxcool/do-something?input=${inputNumber}`, {
    method: 'GET',
    headers: {
        'Content-Type': 'application/json',
    },
})
.then(response => {
    if (!response.ok) {
        throw new Error('Network response was not ok');
    }
    return response.json();
})
.then(data => console.log(data))
.catch(error => console.error('Error:', error));

That didn't work. Calculate.js:29 Error: Error: Network response was not ok

I thought i can just use my Browser and check if i can find that Url.

https://ajax-typo3-test3.ddev.site/ajaxcool/do-something?input=5

Error:

404
Page Not Found
The page did not exist or was inaccessible. Reason: The requested page does not exist

I hope u know what i did wrong and that you can Help me, Thanks!