First, back to the OPs question...
One way to do this on Mac is a little less elegant than on the Windows version but it is easy to do in just a few extra seconds.
(1) First change your number of Choruses = 1 (right on the GUI beneath the MEMO button)
(2) Change the bars = 48 (also on the GUI right beside the number of choruses in the "End" window)
(3) Select your 24 bars and COPY them.
(4) Click on the newly added bar 25 and paste the copied chords. You will now have 48 bars with your original 24 bars copied twice
(5) Transpose all 48 bars *down* by 2 semitones (using command: Control-Command-5 pressed twice, or twice using menu Edit > Transpose > DOWN 1)
(6) Click again on bar 25 and repaste the same 24 bars which are still saved to your clipboard from before. Now you have what you want but it needs to be transposed up again.
(7) Transpose the entire song back up 2 semitones (using command: Control-Command-6 pressed twice, or twice using menu Edit > Transpose > UP 1).
Voila. Some of what you want in just a few quick operations. But it may not give you want you want on the notation side of things because the song acts like it is in one key.
I'm not sure that the lack of elegance should be a reason to want a refund for the product or to not buy it in the first place, but if the notation aspect of this is an issue then I guess this solution doesn't help much.
It may be beneficial to PG and purchasers if PG prepared a full disclosure listing of just exactly what the Mac version is missing or can't do as compared to the Windows version.
I agree with this. There are quite a number of things which are available for Windows users only, and it would be really great to have a clear list of which things work and which don't work on a Mac, and also an indication of which things are on the slate to be added to the Mac version in the near future.