most people will advise you to start out with one meal per day to ease yourself into it anyway and find what works best for you - its a very flexible product so you can have fun ‘playing with it’ and see how it best fits your needs. - literally huge amounts of threads on recipes, hacks and advice here but if you have anything specific you want to know - shout out and there are lots of friendly people here who will help. Probably
First you have to decide how many % of your daily calories should come from Huel. 1 scoop has about 200 kcal. As soon as you know how many scoops you want to have per day you have to see what powder/water ratio works best for you. If you want to consume the equivalent of 2000 kcal from Huel and if you use the recommended ratio it would be 2.5 liters just from Huel.
Depending on how much volume you tolerate you can adjust the amount of water per scoop. Or get less calories from Huel, especially at the beginning.
And nobody tells you to drink one shake all at once. And you don’t have to consume the same amount of Huel every day.
Different things work for different people. At the beginning you have to experiment a lot, to find out what works best for you.