To correctly dilute a chemical manually, first, you need to know how much water you will be adding the chemical to. You can then work out how much chemical to add.
Especially for an autoscrubber, make sure you know how big the tank is, and whether you are filling it completely, so you then know how much chemical to add.
E.g. 1:50 = 1 litre of chemical in 50 litre tank* | 1:120 = 1 litre of chemical in 120 litre tank*
*Assumes tank filled from empty with water with no previous solution leftover.
Usually, a 16-litre mop bucket is filled with approximately 10 litres of water. So for a 1:50 solution with 10L of water add 200ml (10L รท 50 = 0.2L) or approximately one cup.