Could you elaborate on the error observed? Also, share the screen-share and logs for better understanding. Is the error only on UI?
Kindly refer to this article, "Pega Robotics - Excel How To". It has details regarding the concept behind excel configuration in Pega Robotics. Hope it helps, kindly acknowledge if it does by marking this post as answered/helpful for larger Pega audience.
An Excel file would need to be created by Excel. The simplest way to do this is to use the Excel connector and execute the Open method. If the file does not exist it will be created. You can then use the Save method to save it to your hard drive. FileUtils.CreateFile just creates an empty file as it is designed to do. It should not be used for your purpose.