Two product lines. One idea behind both: the computer does the arithmetic and shows its working, and a model is never the thing that decides whether an answer is correct.
Everything reachable from here is a demonstration. The figures in it are invented, the sample association does not exist, and every page runs entirely in your browser: nothing you type is sent anywhere, and there is no account to create.
A real association's records live behind a login, on the application, not here. That is not a formality. This page is served as static files, and a login written in JavaScript over files that are already public would be a curtain rather than a lock: anyone could fetch the file underneath it. So there is no login here at all, and nothing here that would need one.