I will answer my question: OneNote is no longer part of the office package, onenote 2016 is going to be the last non-cloud based version, and its development has finished in that way. The standard onenote cloud based version installed in any windows 10 distribution will be the future.
Anyway, we can still download the 2016 version from this link, in wich everything said above is explained:
https://support.office.com/en-us/article/onenote-2016-is-missing-after-installing-office-2019-or-office-365-1844ba87-7248-4bd8-a735-66a52f98e6e5
Just download the correct version and install it. If you have already installed and activated your office professional plus 2019 according to "msguides" it will take the same license, and it will be shown as activated.