Lockbox folder is invalid

Hi, Im Darmawan from Indonesia
I can't speak English for well

Today, Im installed maianlockbox on my hosting.
When I want to setup lockbox
I can't add new lockbox because I can't choose lockbox folder
"" Folder ia invalid


When I read instruction, we just manually add members PATH...

But I don't know how to do this...

How to fix itu?