Question 2:
The formula a ∧ b ∧ c ∨ ¬a ∧ b ∧ c ∨ ¬a ∧ ¬b ∧ c ∨ ¬a ∧ b ∧ ¬c ∨ ¬a ∧ ¬b ∧ ¬c is represented by the ZDD you were given in that exercise. That is true. However, in part a) you should submit the set representation of the ZDD which is {{a,b,c},{b,c},{b},{c},{}} in this case, and in part b) you should submit the Reed-Muller normal form of this formula. You have submitted the above formula in DNF and the system told you that your submission is not in Reed-Muller normal form.
Question 3b
The FDD you were given there has the set representation {{a,b},{a,c},{a},{b},{}}, that is true. From this, you can easily get the Reed-Muller normal form you need to submit for part a). For part b), you have to convert the given FDD to an equivalent ZDD, i.e., you need to represent the formula by a ZDD, and then you should submit the set representation of that ZDD and not the set representation of the FDD. Alternatively, you may compute this from a DNF of the formula.