@lightingclouds I'm glad to read that you solved your issue by updating your OS. For anyone else who comes across this thread, mac users running OS Yosemite have been unable to download games from Origin for a few weeks now. EA is aware of the issue and is working on a solution, which, when available, will be posted in this thread:
https://answers.ea.com/t5/The-Sims-Mac/Empty-Game-Library-Server-Error/m-p/6947610#M13261
In the meantime, updating to High Sierra will solve the problem. For those whose computers can't support HS, El Capitan should be sufficient. Both can be found by searching the app store.
After the update, it may be necessary to run the Origin reset tool for macs.
https://help.ea.com/en-us/help/origin/origin/how-to-reset-origin-on-mac/