I'm new to oUF after using PB4 for some time I've decided to do a new UI for each of my characters and to save all the messing around I decided to get some of the pre-made packs on here. I downloaded the oUF COre as-well as one or two addons to go with it, I moved them into the interface - addons folder, but it doesn't want to load in game. They're enabled and up to date. So what's the problem? I'm probably missing something obvious.
The supported oUF plugins by your chosen layout are normally listed on the layout's page.
Some layouts have plugins and even oUF's core embedded, meaning you don't have to install them separately. That's normally mentioned on the layout's page.
oUF's core, the layouts and the plugins are normal addons. You install them separately in <your wow folder>\Interface\AddOns.
Beware: layouts do not have to support every available plugin out there and not even every possible feature of oUF. Some don't provide all unit frames (raid frames are a common example). Most of them don't have any graphical setup like PB4, so you need at least some basic LUA knowledge to tweak stuff to your liking. Most layouts lack character specific options, meaning you'll end having the same looks and functionality for all your toons.
If you need specific support, you'll have to provide more information: chosen layout, LUA errors etc.