If you get the ARC updates through the Google Play Store with automatic updates, you should already have received 1.0.42 Build 212 (the same as the Hotfix version in production), even if you are in the Beta program in the Play Store.
If you turned off the automatic Play Store updates for ARC, you can update it manually in the Play Store.
If you are installing Android packages manually from APK files, you have to install updates manually. The link below is the latest release announcement in Early Access. Not sure what the ARC version in the APK download is, and if it includes the Hotfix, but it was released after the Hotfix in production, so I’d guess that it’s included. See the links in the announcement: