You can download test files to see how WBmerge works. The files can be downloaded from the free trial page - https://www.workbooktools.com/free-trial.
Remember the 14-Day Free Trial is limited to merging 3 workbooks, but there is no limit on how many workbooks you can Validate Only.
There are 10 test files stored in a single compressed ZIP file. Once you download the ZIP file, you will need to right click on the file and select "Extract All".