Needing some help with the new release of VirtualDJ

Hello everybody there!!
I'm a bit confused so hoping someone can make me see the "light".
May you guys already know VirtualDJ. It is the most known digital djing software..
Well.. the thing is, it has a new release http://www.virtualdj.es" rel="nofollow" target="_blank" class="href wrap_href">(VirtualDJ 2021) and it includes dynamic stems / signal separation mixing.
It means that you can “de-mix” a finished track. So, to isolate parts of a track is now possible!!!
I've already got it but haven't gotten yet how to use that function.
By Whatching videos it looks easy, but i don't know how to configure it so that the same options appear
Please, It would be nice to get some help in case someone knows anything about!
Thank's a lot!