We have enhanced workflow to let you use Microsoft Excel templates to create Excel workbook .xlsx files. The resulting Excel .xlsx file can be included as an email attachment or archived using the SaveFile workflow action.
For more details see https://help.appsheet.com/en/articles/3404478-microsoft-excel-templates
The Microsoft Excel template always produces an .xlsx file. You cannot use an Excel template to create a PDF file.
Because the feature is very new you may encounter problems when using it. Please feel free to report them.