Curtnos

It isn't customizable at all. 
Even as a developer, you cannot curate content that is specific to a Member profile. The Squarespace stance on this is that only Squarespace-generated content, such as purchases and member areas should be stored within a profile. In their opinion, other information such as achievements should be stored in a third-party system. For example, you could embed one of the third party learning management systems and use this to store to track student progress. 

Site URL: https://www.mylastbraincell.org
I'm putting together an educational website (yet to be relased, but www.mylastbraincell.org with password beta-test), but after chatting to a freelance developer it is seeming like I can't produce what I want on SquareSpace. A major capability that I need on my site is interactivity with JavaScript modules, stuff where a student can move things around and observe how the system changes. I've attached a very rough idea of where I wanted to begin with the developer, and I would be so unbelievably appreciative to anyone who can tell me how to achieve this on Squarespace or if I need to start over on a different platform which you build up from nothing. I am in the process of learning JS/CSS/HTML but wanted to begin with general templates to get the interface out of the way while I just did the JS function attached to each button.