Install the "PLAAF OPFOR 'Urban' (Fictional)" folder into EITHER of those two folders:

SavedGames/Users/(You)/DCS.openbeta/Liveries/J-11A
If you dont have an Liveries and J-11A folder, create them.

OR

(Game Install) DCS World/Core Mods/aircraft/ChinaAssetPack/Liveries/J-11A



Install the Files inside the J-11A folder to 
(Game Install) DCS World/Core Mods/aircraft/ChinaAssetPack/Textures/J-11A