hello and welcome !
In Flarum there's no concept of categories. Tags serve as "forums" and you can nest them to replicate the concept of "categories" as found in other software.
For example here on Discuss we have the Support top-level tag and sub tags like Installing and Updating. You have some settings to choose how many tags should users select, though there's not really a way to force selecting a second-level tag and not a first-level one.
KaiLord it only talks about it being Flarum beta
That's because it is indeed still in beta.
But I suppose you mean you can't find anything else in the admin section ? The admin panel has other tabs. If you're on mobile you can bring up the navigation by clicking on the header.
