Looking at the XML that you have uploaded the possible issue could be, that you typing the wrong path in the input dialogue box.
A better approach for creating folders/file dynamically will be this.
Here Folderlocation is a variable which stores the location of you folder. This is the expression i have used to create folder with specific names :
Here MailSavedbyBot is my root directory where I want my new folders with the specific name to be created.
once you have made your Bot to traverse the location where you want to check for a particular file then use Path exists activity to check for that file. if you know the name of the file to be checked, then you can hard code it, or else you can create an input message window where you can give the name of the file and later on pass it as a variable.