I bought Magix music maker 2020 premium and later this year 2021 was released for which I didn't received any upgrade updates to upgrade from 2020 to 2021?
Because the 2021 version of Music Maker was a major upgrade, principally to a 64 bit engine, I believe it was a "paid" upgrade for ALL users. As to why you didn't apparently receive any email notification I'm not sure but I believe all such notifications now come via the program itself, i.e. when you run MM it should display a pop-up with the message that an upgrade is available.
However, if you have deliberately turned off the Update Notifier (perhaps because you were "tired" of receiving pop-up messages) this situation is one of the "problems" that can then follow!