Great bit of kit, capable of ripper brews. The numbers on the hopper are irrelevant, other than giving you a point of reference to return to if needed or to judge extent if adjustment of grind.
It's no different to setting up any other grinder.
Start by keeping the dose and tamp pressure consistent to decrease the variables you are playing with so you don't end up chasing your tail.
Grind a double dose into the double basket, settle grinds, tamp and pull a shot. See how it pours. If too fast, repeat with finer grind until you get the pour you want. Likewise if chocked, make grind coarser. It really is that easy, no need to over complicate it.
Once you are in the correct grind setting "zone", it should only change by a marking or few either way as beans age or you have different brand.
You must also use decent and fresh beans.
Enjoy the brews!