Specifically, this means: Anyone who already has a valid Windows 10 license and a sufficiently good computer can upgrade to Windows 11 free of charge. However, there are some hurdles here that mean that not all users will be there right from the start on October 5, 2021.
This is how Microsoft provides information on the subject
First of all, those users who buy a new PC from October 5th will get the new operating system. All other users are then gradually taken along – at some point they will be notified that the update is ready when you look under “Settings> Windows Update> Check for updates”. However, it can happen that the whole process takes a while. Microsoft has announced that all devices that are eligible for the upgrade should be supplied by mid-2022. So there is not even a guarantee that you will get the update this year, unless you do it yourself and force the update via a Windows 11 ISO, for example.
Eligible devices are, by the way, those that meet the official system requirements. There has been quite a bit of controversy about this since Microsoft’s first announcements. Although Microsoft ultimately made some adjustments, Windows 11 will at least cost many users the price of new hardware.
But if you don’t even have a valid Windows 10 license, you won’t get Windows 11 for free. The respective license fees for the individual editions that Microsoft brings onto the market are then to be paid here.