Hi @Lavitas Macutis,
Thank you for sharing all the details and screenshots, that really helps. As Anubhav mentioned, I see from your screenshot that you have the MATE plugin and the QR Checker installed. On the Creative Cloud desktop app, for each installed plugin, there's an option called "Where to find it" if you click on the three dots next to the plugin name. This section guides you exactly where to access the plugin within the application.
As per that guidance, you should find the MATE plugin and the QR Checker under Windows Menu > Extensions in InDesign. Please give this a try and let me know if you're able to access it there.
Looking forward to hearing how it goes!