To sideload the Semaphor application on your mobile device, make sure you have adjusted your android device settings to allow for installation of sideloaded applications. Navigate to www.spideroak.com/opendownload and find the Semaphor installer for the Android application. Select it and begin the download process. Once downloaded, run the installer and Semaphor will be ready to go.
We moved away from offering Semaphor on the Google Play store because currently the Play store requires the applications it hosts to be 64-bit, and Semaphor is a 32-bit application. In order to be able to deliver a secure application with updates we can control, we've taken the application off of the platform until such time as we can be more confident in the ability update our application on the Play store.