Hi
That is very odd. It seems to be a problem that affects players sometimes but I'm not sure why. On a computer with a disc-drive, if the player uninstalls the disc version and then starts using Origin, that message sometimes comes up because they have not completely and cleanly removed all the disc-requiring installation files. But in your case that can't be happening because your Macbook never had a disc version to begin with.
The only thing I can suggest is that you cleanly uninstall the game from the Macbook, remove Origin as well and download a new copy, and try again. Be sure to choose the right superpatch for the Origin version of the game.
If that still doesn't work, you may want to contact EA customer services to see if they can advise further.
I'll paste below some more detailed instructions.
Good luck!
Caspin
Clean uninstall
When you uninstall TS3 games on your Mac using the uninstaller, the game leaves behind stray files and isn't completely removed from your computer. These files may conflict with future installations. It is best to completely remove them. BluebellFlora's website provides a guide on how to do this:
http://bluebellflora.com/the-sims-3-on-a-mac/how-to-do-a-clean-uninstall-and-reinstall-on-a-mac/
After cleanly uninstalling, install the base game and patch it up to date. If you cannot update via the Launcher, download and apply the latest cumulative manual patch (called the superpatch) for Mac.
Check that your game works properly. Then install any EPs and SPs that you own, in order of release date.
To download and install games through Origin
Download and install the Origin client for Mac and make sure it is up-to-date. If you already have Origin on your Mac but are having problems with downloading or installing games, delete the client and download a new copy (this sometimes fixes issues with downloading). The latest version can be downloaded from here: http://www.dm.origin.com/mac/download
Additional advice on how to download games (thank you Tremayne for this tip):
When downloading from Origin, do NOT use the first install icon. Move your cursor over the game cover and click on the information (letter i) and then click on the install button from there. For some reason, downloads from Origin frequently become corrupted. Using the i reduces the chance of your download being corrupted. If you have already been unfortunate and have a corrupted download, then it is important to remove all traces of this before trying again, by doing a thorough, clean uninstallation first.
Are you running anti-virus software or any clean-up applications? If so, disable these, as they might be deleting files that Origin needs. A fast, stable internet connection will also help you.
Patching
Many simmers find that patching their game via the "Game Updates" tab of the Launcher does not work properly. It is then better to download and apply the manual superpatch. It is important to download the Mac version rather than the PC version, and to pick the right one for your region.
Instructions and the links to the downloads can be found in the Mac section of the forums at thesims3.com here:
http://forum.thesims3.com/jforum/posts/list/549552.page
If you use any mods or custom content, be sure to remove them before patching.
