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Once you have the APK file, you need to “sideload” it onto your Android device. If you are unfamiliar with that process, see here: https://androidcommunity.com/how-to-sideloading-apps-on-your-android-device-20180417/
Now you should be up & running!
Verification Codes
For testing, it’s likely that you will also want the ability to generate Verification Codes.
To do this, you need access to (yet another) server.
https://verify-gaen.extremesolution.com/home
To be able to create an account on this server, you’ll need your email added to an approved list. Send a DM to Art Gibson on Slack, and he will add your email to the list.