I'm trying to try out BusyCal, but it requires an app-specific password, and provides an outdated link to old information about how to do this.
The page refers to an "App Specific Passwords section" under the Security settings of the Apple ID site's account management page. This section does not exist under Security, or anywhere else on that page.
There is almost certainly still a way to create app-specific passwords, but even Apple can't keep their help up-to-date, and even a company whose main product depends on users finding this information can't provide it, so Stack Exchange seemed like the best place to turn.
How (and where) do I create an app-specific password these days?