I purchased a Business Tax program from Staples that can't be downloaded on a Mac. Can I use the licence for an on-line tax filing?

No. The codes for TurboTax Desktop will not work with TurboTax Online & vice-versa.

You can use the form on this TurboTax Canada FAQ to request a refund if needed: How do I get a refund for a TurboTax product?