We had a friendly gate attendant who greeted us. Based on reviews, I thought it was cash only, but she informed us that they definitely accept cards. Don't fret if you don't have cash.
We walked around with three adults and a two year old. We braved a path with a jogging stroller, and my toddler walked for a bit. It was steep, just as the description said, so I don't recommend bringing a stroller unless you are sticking to the road and the boardwalk path. I decided to go for it anyway.
The bathrooms in the refuge center were clean, cool AC, and a small gift shop along with very cool animal exhibits. I loved the turtles and the hawks the most.
We took a little sidewalk circle path to the left upon exiting the center (10 minute path, maybe) and saw 4 creatures back to back! First was a bunny, a lizard, and then a writing spider and two walking stick insects. The next creature we saw after that was a fawn and its mom upon exiting the park. Unfortunately, we did not see any bison like the pictures. Maybe we will try again in the fall!
We had a great adventure here and really enjoyed spending time in nature. It was peaceful to be among the big trees and away from crowds.