Urgent: Member Areas - Editing Access Denied Page

I have member areas set up but I need to change the "Access Denied" page to one I've put together. I don't know why Squarespace is so restrictive with the editing of this page. It forces you just enter some button/description text and gives you no editing capabilities of the page itself to add or change anything.

The current squarespace generated Access Denied Page(s)
- https://www.blackom.com/watch 
- https://www.blackom.com/read 
- https://www.blackom.com/listen

The page I need it to be or look like - https://www.blackom.com/membership-access

This is urgent and any help is appreciated. I'm also going to contact Squarespace about it tomorrow morning but that'll probably amount to nothing.