Auto-numbering from actions

I'd like to use this one, but I'm a bit lost how and where I can use it.
For me the best way would probaly be to put it in an action group.
May someone can point me to a way on how to archive this?
I'd like to apply the numbering automatically directly after the change of the genre (as shown in the screenshot).
To run the auto numberfunction with an action would be also fine for me.

I am not quite sure how MP3tag should "guess" the (correct) track number ...
To get a sequential number:
Action of the type "Format value" for TRACK
Format string: %_counter%

I'd like to run the action after i receive the trackinformation i.e. from discogs.
So the files are already in the right order. I only would like to add automatically tracknumber/total and (probably not possible) discnumber/total.
But anyway, it seemy like I'm on the right track with your answer.