Hi Petr KK
Based on your description, you may have installed the wrong version. Windows Server 2022 Standard Core can only be upgraded to Windows Server 2022 Datacenter Core, not to desktop. Therefore, you will need to reinstall Windows Server 2022 Standard Desktop and then activate it with your license key.
If you need further assistance about system activation, please see Support Center Contact Info. | Microsoft Learn.
Hope it helps.
Kind regards,
Lei