The VAT Filer is password protected by design as requested by HMRC to prevent data being manually keyed in.
You will need to use the ‘link cells’ button on the data link tab.
If you are unsure how to link your source spreadsheet to the VAT Filer, we would recommend that you take a look at our demonstration video, using the link below, that explains in detail how to do this
https://www.absoluteexcelvatfiler.co.uk/pages/absolute-excel-vat-filer