excel XLS to XML - mapping issue

Hello everyone!

I have a big issue in a very important project for me.

At the beginning I will add that I am not very versed in mapping in Excel. I have read many threads from this forum and the microsoft manual, but I do not know exactly in which direction I should go, and I really need this solution ...

I am working on a solution which is based on a specific XML template. Template in the attachment under the name "Template_xml.txt".

I want to be able to open this file in excel as XML map and edit any cells. I also attach the excel file as "Template_excel_xml".

Then the excel file is to be saved as XML unchanged.

At the moment I cannot export the edited excel to XML because it shows the message:
"unable to export or save xml data. maps xml in this workbook are not exportable"

I know it's possible to write XLS to XML with a VBA macro, but I can't do it at all ...

I am asking for help, thank you for any advice ...