I can't see what to do, how to search, how to browse, or, in short, how to make use of this.

It needs something more - it feels like it's seriously lacking in discoverability. It's currently also failing to load:

https://my.mindnode.com/83qmKgoATj8TyKzprzsPfoirxa2g9WmFGx3x...

I've bookmarked it, but I don't know what to do with it.