Sounds like you are actually exporting the schedule settings as an XML file.
This is for later importing the schedule into other Archicad files.
To open in Excel you need to open the schedule (not the scheme settings) and "Save As" with an .XLS or .XLSX format.
Barry.
One of the forum moderators.
Versions 6.5 to 25
Dell XPS- i7-6700 @ 3.4Ghz, 16GB ram, GeForce GTX 960 (2GB), Windows 10
Dell Precision 3510 - i7 6820HQ @ 2.70GHz, 16GB RAM, AMD FirePro W5130M, Windows 10