Make the correction specific enough to use.
What happened
During your answer explanation, you treated “Only members may vote” as if it meant that every member may vote. The statement makes membership necessary; it does not make membership sufficient. So we know that every voter is a member, not that every member can vote.
What to do next time
When a conditional (logical) statement uses “only,” use it to identify the necessary condition and confirm the direction of the relationship before drawing an inference. Here, someone who may vote must be a member. Being a member alone does not establish that they may vote.
We test that correction on new questions. And when you get comfortable, we move on to the next skill.