There are many ways to perform HTTP redirects, here is one example

https://wiki.mikrotik.com/wiki/HotSpot_ ... login_page

const express = require('express');
const app = express();

app.set('view engine', 'ejs');

app.listen(80, '192.168.10.254');

app.use(express.static('public'));

app.get('/login', (req, res) => {
    res.render('login');
});
app.use((req, res) => {
    res.status(404).render('404');
});

AFAIK mikrotiks web server cannot host _any_ server side languages.

The example shows how to redirect to an external PHP server, use that as a guide to redirect to your node.js application, the logic is exactly the same

I tried to open the link in Yandex with a VPN - eventually it's been opened. Well, Ukraine blocks a range of Russian's IP addresses who knows it might be the reason.

For goodness sake! Is there any MikroTik representative alive?

Another way to contact Mikrotik support is to reach them at support@mikrotik.com.

Yes, the above poster is correct. You should consider external authentication, because (as another poster pointed out), MikroTik HTTP server can only serve static pages, there is no server side language support at all.

Is there any difficulties to implement an external link and provide access to a routerOS through API?