Hey--
Did you any get any kind of error message when you tried downloading Riverview or did the launcher say it was successful.
Also, can you make sure you are patched to the latest version? The launcher is not always correct if you are relying on the last tab and using the refresh button. To check the patch of your base game on a Mac, the easiest thing to do would be to open the file "Version.tag" that is in your Sims folder under Documents. It is a text file, you can open it with the application "TextEdit" if it asks you what to open it with. Make sure the version number that file says starts with 1.50.