My family went to the zoo last week with a reservation I saw a share on Facebook about members may go to zoo after 3pm without a reservation due to the numbers were low after that time. Is that accurate?

Yes, after 3 you don't need a reservation.

I had no issues at all. However I would urge you to get your tickets ahead of time by going to www.columbuszoo.org/reservations

Yes, that is correct.

I saw the same post on Instagram directly from the zoo so I assume that is correct.

I am not a member and I went on sunday(father's day) with just a reservation ticket at 1030 am and had no issues. Hope this helps