Clone a Willy Alginate Powder

Hi guys! This is my first time making a silicone toy and we bought a clone-a-Willy kit. However I used up all the alginate powder. I accidentally only added 1 1/2 cups water when it wanted 2 1/2 cups. So the mixture was too thick.

I’m buying more alginate powder, for generic moulds, not specific penis moulds, but the instructions on this other brand say use a 1-1 powder to water ratio. Can I safely increase the water? And go against the instructions?
These other powders are for hand and foot moulds, and penises are a bit more squishy than hands. So I assume I can add more water to the powder?
Please give me any tips!
Thanks 😊