[imported_Necro]

Stygians is not a requirement.

Mondain's Legacy should work perfectly. It can be located here

You then must PATCH uo by using uopatch.exe (It can be found in the Ultima Online Installation Directory). Even when it says "Complete" run uopatch.exe 2-3 times again as sometimes it doesn't go all the way.

You then have to use either: The IN-X PATCHER located here

OR

You can download the package and manually replace the files in your installation directory. The package is located here

Are you using Razor or Injection? Injection uses client 5.0.1 and Razor uses any client I believe. Clients are located here.
Technique has posted a very good guide on how to setup Injection which can be located here.
Remember the server address for the shard is: login.in-x.org port:2593


NOTE: If you are using Windows Vista or Windows 7 you usually have to run the client AND Injection or Razor BOTH in Windows XP Compatibility Mode (You have to right click the .exe file and under the compatibility tab you can select Windows XP)

I know you said you are running MAC OS but the note is for anyone else who is having problems.