Owners of Macs found out when they bought some of Valve's new hardware that their computers couldn't make either the Steam Link or the Steam Controller work. Despite them having been advertised to work.
Valve are sending out apology emails now to all affected, hoping to make up for the oversights. They have cited the cause as "temporary software issues" and say they will probably last a few weeks before they can be fixed.
"We want to apologise for the delays in providing full functionality for the Mac platform. We're doing everything we can to resolve the issues. For the latest fixes and functionality, we recommend that you opt in to the Steam client beta."
An upcoming update will add support for Macs so that you can use the Link to stream from them, as well as adding support for video,audio and controller input. Gamepad emulation will also be supported on Macs for the Steam Controller.
Until then, Valve are adding the Valve Complete Pack to the Steam accounts of affected customers, giving access to them for all Valve games; past, present and future. It's free and can be kept even if the customer opts to get a refund on their hardware. The returns policy has also been extended to 60 days and Steam will also cover postage for those wanting a refund.