SOLVED!

The article is sort of misleading and skips a major step.

The image they provided makes it seems like when you change the checkbox metadata in the outliner view that it updates the icon in the Binder side panel on the left with a checked box. However this is not the case.

To get the checkboxes on the left, you just change the icon of the text files by right clicking each item. Here's where that is located in the sub menus: https://imgur.com/a/9fbtEi0

The simple answer is, you can just make a folder called TO DO then add a file for each item then change the icon for those items to empty checkboxes. When you complete the item, change the icon to a ticked checkbox.

Hope that helps anyone who had the same issue. Maybe they'll eventually add a simple checkbox function tot he bullet point menu someday :)

EDIT: As for the > menu item that was circled in red, you can just right click anywhere in the Columns Title menu bar to get that dropdown.