Forgive me if this is a very obvious question. I just can't find the solution for the life of me.
I've installed and activated the following plugin: nodebb-plugin-category-notifications (https://github.com/NodeBB/nodebb-plugin-category-notifications#readme)
I then rebuilt & restarted the forum. I was able to get into the admin screen.
According to the description, my users should now have the ability to subscribe to categories. How do they do so? I don't see a button or option anywhere in proximity to the categories.