If you encounter a problem downloading the latest patch (usually an "RT patch error" appears), you can download and install the patch manually which should solve the problem.
First, make sure Family Tree Maker 2014 is closed. Then go to the Family Tree Maker help pages at:
Follow the instructions for the manual installation - start at step 2 and download the patch (I'd recommend downloading the .exe file).
After it has downloaded, run the .exe file, and this should take you through the installation process for the patch. Once installed you should be able to start the program.