Two days after seeding OS X 10.11.4 El Capitan beta 2 and iOS 9.3 beta 2 to members of the Apple Developer Program, public beta testers who are signed on the Apple Beta Software Program can now freely deploy these new beta builds on their Mac, iPhone, iPad and iPod touch devices.
iOS 9.3 beta 2 is available as an over-the-air update in Settings → General → Software Update on enrolled devices. OS X 10.11.4 beta 2 can be downloaded through the Mac App Store's Purchased tab for those who are enrolled in Apple's beta testing program.