I checked your provided files and they are of BIFF7 (Excel 95) format. As Aspose.Cells supports BIFF8 or greater formats (Excel 97 - Excel 2007). I think you may try the following steps:
Open your template .xls file in MS Excel (e.g..,Ms Excel 2003 or 2007).
Save the file As "Microsoft Office Excel Workbook".
Now you can use Aspose.Cells to open/manipulate the file for your requirements.
We recommend you to kindly try upgrading to and use latest version of the product which includes support for older BIFF7 (Excel 95/5.0 - 2003 Workbook) formats with enhancements now:
Also, see the document for supported input and output file formats by Aspose.Cells: