Check your "Save as..." options in Quattro Pro. If you can save it as an Excel file of any type (i.e., Excel for Windows) the Mac version should open it without a hitch.
Otherwise, try saving as a SYLK file and try it.
Otherwise, brute-force it. Copy and paste from Quattro Pro into Excel for windows, save in excel for windows, import to Mac from floppy or otherwise.
Honestly, though, the Mac version of Excel will open any DOS of Windows Excel file. I've done it as I have a Mac at home and a Windoze machine at work.