As someone already said, when you use Add Library, the folder you select MUST be a folder one level above  your Runtime. 

For instance, my V4 Clothes are in a folder on an external drive. The folder is called V4 Clothes, within it is a folder called Runtime, and within that is all the content that I installed. When P13 prompts you to add a Library, you would select the V4 clothes folder and it is added.

The folder is not moved or changed in any way. The folder technically can be added to P13, 12, 11, furore 14, etc.