How to upload multiple files of the same file type on a web application

Hello All, I’m trying to test a web application using Katalon Studio.

This application requires me to upload files of a specific type onto it in order to perform certain operations. However, I am unable to upload many files of a file type(I want to upload 10-15 files of *.txt type for example) onto the web application. I have tried the WebUI.uploadFile() command and also tried looking for a solution in different forums in vain.

I would appreciate if anybody would help me on this.