Hey @jkwan314! You need to specify the wires you want the probability distribution to be over:
@qml.qnode(dev, interface='torch')
def generator(w, num_layers = 3):
rotation_layer(w[:num_qubits])
for i in range(1, num_layers*2 + 1, 2):
entangling_block(w[num_qubits * (i) : num_qubits * (i+1)])
rotation_layer(w[num_qubits * (i+1) : num_qubits * (i+2)])
return qml.probs(wires=range(num_qubits)) # <<< here
See here for more details. Hope this helps!