Can't Redeem Code for Sims 4

This is a bit hard to explain, so I'll just list the details and my problems.

- Have disc copy of Sims 4 for PC (installed)

- Have Mac that I want to play Sims 4 on

- Game doesn't show up in "My Games"

- Redeemer Code on inside of box doesn't work ("Code has already been used")

Please help.. thanks

(Should also point out that I have a Mac Mini - no disc drive)