How do you have it scheduled? The RPA software can only take a screenshot if the system is unlocked. See also How-to: Windows Task Scheduler, Automate RPA tasks
Log file: If you have the XModule extension installed, the log file is created in Home Folder / Logs e. g. C:\Users\ulrich\Desktop\uivision\logs
See also: How to store logs of each session in a single text file - #7 by ulrich