Since Steinberg doesn’t seem to provide any info here on the forum about the new way you have to activate your product (Cubase),
I hope, maybe this will help:
If you are getting the error “e-Licenser version too old” you are probably trying to activate using the Download Code, which won’t work! The new undocumented?? way of activating Cubase, is to paste the Download Code in the Steinberg Download Assistant’s “Enter Your Download Access Code” -field, in the top left corner, and it will then return the Activation Code, which you then will use to Activate your licence in the e-Licenser, or directly from the Download Assistant, as shown in this video https://www.youtube.com/watch?v=_Zre7x9P5Ek
So the confusion, (at least for me it was), seems to be that people are trying to activate their product using the Dowload code (which you got in your purchase confirmation e-mail), instead of the actual Activation code.
PS. Here’s a video about using the Steinberg Download Assistant. If you’re already familiar with the new Download Assistant, You can skip to around 3:00… https://www.youtube.com/watch?v=_Zre7x9P5Ek