Since I'm a PC user and not a MAC user, I don't know if I can help. I think the number of genealogy software makers has been narrowed down in the past few years. A lot have gone out of business and some have been bought up by others.I use FTM (Family Tree Maker) and like it. I also have Legacy 5.0 which is a product of the LDS church which produced PAF.I'm only familiar with the old PAF versions and the Legacy 5.0 is much superior to the old PAF.I think FTM has their software available for MACs, but not sure. It (FTM) is probably the most widely used genealogy software. Some of the other brands of software can be uploaded into FTM, but you might lose some fields of information.
Can you find out what software was used to produce the new information you have received?That is a starting point.If it's been done on some old type software, you may have trouble finding a newer software to read it.Keep asking in these forums for information. If you find out what software it was written with, then ask FTM if you can upload it into their software.