https://www.amazon.com/dp/B006H1ZDBC/ref=cm_sw_r_cp_api_i_vNGyBb9F2F9F4

They specifically call out "Chairs with Legs". If you bring one of those stadium buddy style seats you should be ok (like this one -> https://www.homedepot.com/p/Coleman-Stadium-Seat-Blue-2000020281/203640015) This is basically just a cushion and it doesn't say you can't bring in a cushion or pillow.

You're going to want something more like this that keeps the back lower.

Or this one, which is like one in the picture Desert Trip posted.