Per title: apparently there's no way to set the water volume used by my DeLonghi espresso machine on the TM BM 2...??

I saw one of the YouTube baristas use the Timemore BM 2 to dial in his espressos. I found the pour over option an extra bonus for when the mood hits so I saved up and bought it.

Primarily, I want to dial in espresso. But I can't figure out how it determines extraction ratios if it doesn't know how much water was used (and thus, how much water is retained). I can set EVERYTHING it feels, but the water volume or weight I used...

Help? 😅

Edit:
The scale and app show a lot of variables, like extraction rate. Yes, I'm just starting out so I could be asking very dumb questions here.

I can set some variables like grams of coffee used, temperature, etc. But I cannot set how much water was used. Say, my De'longhi La Specialista uses 30ml of water for each shot. Is there an option to enter that in the black mirror app? That way, it could give the correct extraction ratios, no? Now, to me, it feels like it's just throwing out numbers. Of course, flow rate graphs and total weight etc are correct.

Thanks!!