help with conversion

Do you know what version of QWin created the file?
What version of QMac are you running?

AND, in general, you CAN import QWin data files into QMac ... but not any QWin file.  There are date restrictions as to how old that QWin product can be and how recent the QMac product is.

ALSO, the QWin to QMac conversion is a one-way street.  The QMac to QWin conversion is hopelessly broken ... has been for several years.

Karen Anne Mahoney said:

Somehow I figured how to convert the file and got it going on my macbook! Thank you! I will likely keep the program on my mac only from now on. 

Glad yo figured it out.

NOTE: Be aware that at this time, it is very difficult to convert back from Mac to Windows, as there are many problems with the reverse conversion process.

I suggest that you make sure that Quicken 2018 for Mac will meet your needs, since it was re-written from the ground up (first with Quicken Essentials in 2010, then again with QM2015 onward) and is not the same product as the Windows version, so there are some features that are still not there e.g. full loan amortization*, 2-line display, QuickMath, or are not as fully developed yet, e.g. Customized Reports, some investment performance reports and stats  (therefore some data may not carry over). You can start here:
http://www.quicken.com/mac/compare
https://www.quicken.com/whats-new-quicken
https://www.quicken.com/mac/upgrader-compare

*NOTE: Support for fixed rate loans has been released as of  QM2017 v4.5.x but there is no announced timing for support for variable rate or simple daily interest loans.

You may want to review the List of Obstacles and Hindrances for Migrating from QM2007 or QWin to Quicken for Mac. Add your vote to any features that are missing for you. Your VOTES matter!

Be aware of data that will and will not carry forward: 
https://www.quicken.com/support/what-data-gets-carried-over
(A couple more things to note: historical currency rates are not migrated AND currency conversions of transactions are not migrated).

Then look at the updates since the original release here:
https://www.quicken.com/support/2018-release-quicken-mac-release-notes
You will also want to look at a more detailed comparison done by a SuperUser which also identifies nuances not mentioned elsewhere (and read on for comments from other users too on that same discussion thread): 
https://getsatisfaction.com/quickencommunity/topics/can-anyone-who-has-switched-from-2007-to-2015-he...
Take a look at the following videos to give you a better idea:
https://www.youtube.com/user/QuickenMac

Note that there are many differences that are rather subtle, that are not necessarily identifiable via documentation, for example, the 12-month budget feature does not allow including transfers, including investment income, selecting specific accounts,  or have rollover capability.

If you find that QM2018 does not meet your needs, the alternative is to run Quicken for Windows in a virtual machine on your Mac. There are 5 popular products you can use: Parallels, VMWare Fusion, Oracle VirtualBox, Bootcamp or CrossOver. The first 4 require you to also buy a copy of Windows. The first 2 cost $50-80, the third and forth are free. CrossOver also costs about $50-$80 but does NOT require you to buy Windows.

If you plan to keep your PC & Mac, you could also run Quicken on the PC and use remote access (several free options, e.g. NoMachine and Teamviewer) to access Quicken from your Mac  (or even a tablet or phone) (see this great article for complete review of many options (most are free): http://machow2.com/rdp-for-mac/ ).

(If you find this reply helpful, please be sure to click "Like", so others will know, thanks.)

Karen Anne Mahoney said:

Somehow I figured how to convert the file and got it going on my macbook! Thank you! I will likely keep the program on my mac only from now on. 

Understand that Quicken for Mac is a relatively new product built from the ground up (starting in 2010) and is NOT a continuation from the old QM2007, so there are some features that are still not there or are not as fully developed yet. 

If you are interested in some historical background on how we got here, see the following compilation:  
Why does Quicken for Mac not have feature parity with the Windows versions?

(If you find this reply helpful, please be sure to click "Like", so others will know, thanks.)