The company just announced a beta tester program on it's community forums. You'll need to own a Robin, of course, and fill out an application form that includes your name, IMEI number, serial number, mobile carrier, and other details.
Nextbit cautions that chosen testers will encounter bugs, and are expected to provide feedback to the development team. As the post says: "Keep in mind the beta program is not intended as a way to quick way to cut to the front of the line for new software. It’s a responsibility, and you accept risk on the behalf of other users." If you own a Robin and want to help out, head to the company's community forums and fill out the application.
Why this matters: Among enthusiasts, software support is as much a selling point for Android phones as any other feature. We expect the rapid release of new Android versions, monthly security patches, and new exclusive software features added for the life of our phones. Nextbit promised that the features of its cloud-backed version of Android are just the beginning, but it's a comparatively small company and will need to lean on the community to release solid software updates.