In order to use the IDE to develop cross-platform applications, you need to install and run the Platform Assistant on the target platform. The Platform Assistant file name is 'paserver', the remote application server. If you use the default port number (64211), you should be able to use the Platform Assistant without changing any parameters.
You will need to transfer the PAServer installer to your Mac OS X machine, and run the installation. The PAServer installer can be found at:
C:\Program Files\Embarcadero\RAD Studio\n.n\PAServer\setup_paserver.zip
PAServer is a console application. Open the Terminal window on the Mac, go to /Users/<your accountname>/Applications/Embarcadero/PAServer, and then type:
PAServer will ask you to provide a password to connect into PAServer (you can define a password, or leave it blank).