Vitamins and minerals have RDA (recommended daily allowance) targets set by the USDA … Huel meets or beats those.
The macronutrients (fat, carb, protein) are in ratios that the Huel team thinks is best for long-term health. There are no RDA values established for macronutrients.
You can use a calorie calculator to determine your daily calorie intake to maintain, gain or lose weight and then tailor your Huel mixing to hit that, allowing for non-Huel meals you eat as well. If (for example) you were looking for 2000 calories a day and were going to use 100% Huel then you would be consuming 66g fat, 151g net carbs and 148g protein.
If you add anything to Huel other than water all the numbers change.