Hi RJ2020-123,
Thank you for reaching out to Microsoft Community.
Just to confirm, is this the keyboard that you have : Wireless Comfort Desktop 5050?
Yes, you will need to installed the Microsoft Mouse and Keyboard Center to use the full functionality of the keyboard. I'm sorry but the Mouse and Keyboard doesn't have a version compatible with MAC OS which is why using the keyboard with MAC OS, you'll have a limited functionality (check Operating Systems under Specifications : Wireless Comfort Desktop 5050).
If this answer your question, we highly encourage you to inform our Community by clicking on Yes or marking my post as an answer. This will help other members who may have the same issue as you. Otherwise, don't hesitate to update us so we can further assist you.
Kind Regards,
Marrion Y.