Install TurboTax Premier on 2nd computer without internal CD drive

I bought the CD version and used it to install TT on my Windows PC. I installed directly from the CD--no download. Now I want to download on my Mac (since it doesn't have an internal CD drive). I got the error message about the license code already being associated with an account. Just called TT and was told I can't use the get the download now since I initially used the CD.  Rep said I have to choose--so since I used the CD first, I'm stuck using the CD on other computers. The rep also said I could connect an external CD drive to the Mac and then use that to install from the CD onto my Mac. Is this really correct? Thanks.