The Railpro Assistant program (and by extension, everything that connects to Ring Engineering's website) only works on Windows. You can use a Mac and run the program through Parallels, or partition the hard drive and run Bootcamp. Or you can do what I recommended to another Railpro/Mac user: buy an inexpensive laptop from Ebay or Craigslist and use that. You can probably get one for less than $100. Probably around $50 really. It's not like the RPA program is resource intense.
-Kevin
