Trouble Downloading.

having the same issue and it is sending me insane

I've suggest this elsewhere - and, yes, I do understand it is a drastic suggestion - but possible a complete uninstall and re-install. Game, app, the whole-kit-and-kaboodle. Now, that should work ... but if it doesn't, it's possible you may need to look at your system itself. But try the uninstall, reinstall first and see how that goes.

if I uninstall the sims 4 app, will it erase all of my saved data, including expansion packs? I am playing on my macbook. do I need to delete the entire app and folders? 

Unfortunately, yes, all saved data will be erased when you uninstall. The folders will automatically delete (except for the mod folders for some reason, but you can't even get into play a game so that ain't it) and you will have to delete the app from your system through the system tools. I'm thinking in terms of a windows pc here (HP laptop) but would assume the general basics would be the same for a macbook.

dreap1  Your expansion packs will be deleted along with the base game, but they'll be available to reinstall: your account owns the packs, not your computer.  You don't need to delete anything manually—just tell the EA App to uninstall the game and it will take care of the rest.

Your saves shouldn't be deleted when you uninstall Sims 4.  Saves and other user data are stored in an entirely different location: Documents > Electronic Arts > The Sims 4.  The game itself is likely in Applications > EA Games or Users > your username > Applications, although you could have selected a different location when you originally installed the game.  Point is, the game itself gets removed but the user folder does not.

However, I'd still strongly suggest making a backup of your saves.  This is less about the uninstall process than about having an extra copy should something else delete or corrupt your saves.  You can simply copy the saves folder (inside Documents > Electronic Arts > The Sims 4) to another location, preferably an external drive or USB, but if you don't have one handy, a different folder on your Mac would be okay as well.

I was having this issue but I updated my Mac's OS and that stopped the game update. I then clicked manage on my Sims 4 game and clicked repair and now its updated and works fine.