The EDIUS Plus promotion allows anyone who bought EDIUS 9 after 13th September 2019 to get EDIUS 10 free when it comes out.
EDIUS.net have now published how this will happen. If you have a qualifying serial number you need to apply here: https://www.edius.net/plus
and you will get a new “EDIUS 9 plus” serial number that will activate EDIUS 10 when it is released.
You have until 30th April 2020 to apply for this serial number so I would suggest you apply as soon as possible so that you make sure you do not miss out.