How to show the popup/conversion mat on all pages under a directory?

1-  Go to your Campaign settings screen of your campaign, 

2-  In the section « where to show the popups? », uncheck « Show on all pages »

3-  in the text input that appears, enter the path of your page like this

"/folder1, /folder/subfolder/"

PS : if you want to show the popup only on the index/home of a folder like "/blog/", you have to input "/blog/DIR_INDEX", because "/blog/" refers to all pages under that directory.