Well, Aspose.Cells supports BIFF8 or greater formats i.e., (Excel97 - Excel2003). Since your file is of older format (Excel 95 or prior). So you have to convert it to the latest format. The procedure is very simple:
1. Open your template file into MS Excel 97 - 2003.
2. Save the file As "Microsoft Excel Workbook".
Now you may use Aspose.Cells to utilize that file.
Well, your template file will actually be converted to BIFF8 format but your data, formattings, objects etc. will be retained as previous and there is no physical change to your file contents.
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: