Hi there Michael,
I don't know if you know about 'macro's' but it is a code in VBA (Visual Basic for Applications) which expands the use of Excel. I see you are using an iPad to open the file and that is where the problem kicks in.
Unfortunately excel for IOS devices (iPad, Iphone etc.) doesn't support this function (yet). If you really need the macro's to function it is advised to open the file within a windows or osx version of excel.
You can also recognize an excel file with macro's to the extension, which is xlsm (instead of .xls or xlsx).
Good luck!