EA has confirmed that The Sims 4 Outdoor Retreat will be released as a dual-entitlement game alongside The Sims 4 Base Game for Mac in February 2015. This means that Mac users can download the game pack now, and then download the Mac version once the game is released for Mac. Additionally, they have also confirmed that all future content for Mac will be released simultaneously with the PC version.
@Monagas93 Yes, our Game Pack is dual-entitlement.
— The Sims (@TheSims) January 16, 2015
@DanielGrubb8 Mac users will receive all content currently available on PC and in the future simultaneously with PC. 🙂
— The Sims (@TheSims) January 20, 2015