Ascender has no folders for templates. A hundred job templates in one flat list stay a hundred job templates in one flat list, and the usual answer is a naming convention nobody agrees on. Since 25.1.0 there is a Labels screen under Resources in the navigation instead, which turns the labels already on your templates into something you can browse.
What the screen is
The list shows every label that is in use, with its name and the organization it belongs to. The name column sorts, and the search filters by label name or, switching the key, by organization name, both on partial text. A label belongs to the organization of the template's project, so the same word in two organizations is two labels.
The screen is read only, and only labels attached to something appear on it. You still create a label by typing it into the Labels field of a template, and taking it off the last template that carries it takes it out of this view as well. The activity stream button is there for the history of who changed what.
The pseudo-folder part
Clicking a label name opens the Templates view filtered to the templates carrying it: the label is the folder, and the templates are its contents. A template can carry several labels, so it can sit in several groupings at once, which is already more than a folder would give you. The filter is scoped to the label's organization, so an identically named label elsewhere does not bleed in.
One thing to know before you commit to a naming scheme. The filter matches every label whose name contains the text you clicked, not only the label you clicked, so a short name absorbs the longer ones: with dev and dev-east both in use, clicking dev returns both, while clicking dev-east returns only its own.
Name labels so that none contains another, env-dev and env-east rather than dev and dev-east, and express any nesting in the name itself, since labels have no hierarchy.
Where it came from
The screen arrived inside a squashed merge, #120, which is why it is easy to miss in the history, and went undocumented until #657 added a user guide chapter covering the view and the matching behaviour above.
If you organize templates this way, the question worth answering is which gap bites first: creating and renaming labels from the screen itself, or an exact match when you click one.