Sims 3 University not working

Hello,

I recently purchased Sims 3: University Life for my MacBook. I haven't had a problem with any other Sims 3 EP until now. After I installed it and started it up to play, an error message popped up saying: It looks like you have installed an unofficial game modification that does not match your current version of The Sims 3. We recommend that you either uninstall these game modifications or get updated versions of them -- otherwise you may experience crashes or significant bugs. Do you want to quit?

I don't remember downloading a mod for Sims 3 and I've been looking all over the internet for solutions. I do not have a Mod/Packages folder, I've tried locating said mod on my Mac for the past two days and I still haven't found the problem. When I say that I don't want to quit on the error message, the game loads and I can create my sims with University Life clothing and hairstyles, but I can't enroll.

Also, on my Sims 3 Launcher, it won't let me connect to my account, it says I'm offline, even though I'm connected to the internet. University Life icon does not appear at the bottom with the other downloaded EPs. The version I have is 18.0.126.021001