Can't run a macro in Excel 2011

Please accept my apologies for my complete lack of knowledge on this subject.

I have a large spreadsheet that has a very considerable amount of VBA code in the background.

This was written in Excel 2010 and successfully survived the transition to Excel 2013 with nary a glitch. However, I then went and bought a Mac and installed Excel 2011.

The programme no longer runs and I get the following error

Compile error can't find project or library. This occurs after I press CTL M, which in windows launched the macro and brought up a menu of options that I could choose from. The programme is then dropped into the debugger.

Unfortunately my Dad wrote the programme for me and whilst he is fantastic he has absolutely no knowledge of Macs at all so wouldn't know where to start looking for the problem, and also doesn't have a mac on which to test it!

Can anyone tell me if there are certain sequences or actions that Macs won't perform in macros.

The programme is complicated and basically takes the inputs from 3 sheets, examines them and checks for errors, then summates them into different areas and fills in different worksheets to give compilation results.

I need essentially to know whether I am on a hiding to nothing with this and should accept that I will always have to run the programme on a Windows machine, or whether it would be possible to make subtle changes behind the scene to allow it to successfully transfer to a Mac.

Your help gratefully received.
Thank you