I haven't been able to find a solution to this problem, but if you have seen a post please just link it.
I have tried adding addons to my UI from the github post on the forums. My process has been:
1. Download the Zip File
2. Extract the Zip file to my addon folder within Vanilla WoW.
3. Restart my PC
This was how I did it in retail WoW and it worked no problem. However, when I log in, I do not have an Addon folder in the bottom left of my character login screen.
Does anyone know what I might be doing wrong?