Corrupted downloads?

Hey y'all! I have a Mac and have a USB connected to it so that I can have more space when playing Sims. I linked my Ea folder to the one on the USB, and everything is fine when I start my game with no mods, but when I try to download any mods any custom content, it tells me it's corrupted. My game starts normally with no mods, so I know it's not the game that needs to be repaired. I feel like I tried everything. I tried unzipping the downloads in the mods folder just in case they keep getting corrupted in the move but it will not let me download no script mods/mods of any kind. Can someone please help for a million invisible dollars and the key to my sim heart.