Your answer is correct and if the thing is working it would be applicable... but as it stands it is not helpful.

So for all of you out there that CANNOT ACCESS THE CATEGORIES OPTION:

I have just dealt with Support and we cannot get it fixed. But, there are some new steps along the way that might help you:

in the url (using Google Chrome browser) edit the current page location... to go to categories page. it will look like this: "…qbo.intuit.com/app/categories". that will take you to a page that invites you to switch to using categories. This is supposed to work then...but it didn't for me.
I also created a new admin user and logged in with them. They actually had a pop-up to activate it, but it didn't work either.

I will follow up this post with the eventual cause of the problem and solution once we have it.