To install the build, head over to the “Updates” tab in the App Store and check for updates. There, you’ll find the new build ready to install. Just click the “Update” button next to the macOS High Sierra 10.13.4 beta listing and restart your Mac. The process may take a little while, so be patient and don’t turn off your Mac manually if you don’t have to.
So far, there hasn’t been any noticeable changes spotted in the new beta but we’ll let you know if we find anything down the line. As for now, it looks like only bug fixes and system stabilities are present.
Update 1: Messages in iCloud are currently in beta form with iOS 11.3 beta 1 and macOS 10.13.4 beta 1. Users are prompted to enable the feature upon first launching the Messages app after upgrading to either operating system. The feature was first announced as a part of iOS 11 and macOS High Sierra but hasn’t shipped until now.
With the feature, you can sync all of your messages found on your iPhone across devices such as iPad, Mac, and iPod. You also won’t lose any messages you may have sent. In other words, you now have unlimited text threads. Fun.