For the targets, to need 26ppm Ca and 45 ppm bicarbonate. Left to you is what minerals do Ca, gypsum or CaCl2, baking soda, and how many grams of each per gallon, or liter in your case.
The first tab in Brunwater calculates hardness and.alkalinity. The 3rd tab will.give the ppm for minerals in g/L.
Hope this helps.