After iOS 9.3.3 (read: iOS 9.3.3 beta 3 available on iPhone, iPad and iPod Touch), it’s the operating systems OS X El Capitan 10.11.6 (for Mac) and tvOS 9.2.2 (dedicated to fourth generation Apple TV) to receive their beta 3.
If you have a Mac and you have installed OS X 10.11.6 beta 2, just go to the Mac App Store as usual, then click on the tab Updates to download and install the third pre-version of the OS. Like iOS 9.3.3 beta 3, the upgrade is available to developers as well as members of Apple’s public program. It only brings minor bug fixes and improvements.
Regarding tvOS 9.2.2 for developers, we should not expect real news in this beta 3. No changelog has been shared by the firm at the apple. The final version of the Apple TV 2015 operating system should arrive in the coming days, along with iOS 9.3.3 and OS X 10.11.6.