Huel black is fine to have entirely.
The iron issue has been discussed before. It’s to balance out the high calcium you noted. Sodium…well, too much of it is bad, too little of it is bad, and everyone needs different amounts depending on size, how much they exercise, etc.
The only thing I would point out, which may or may not be an issue for you, is that black edition is pretty low carb. So assuming you mean servings as 400 cals of black, if you had 6 servings a day you would have less than 100g carbs a day, a borderline keto diet.