Hello!
It is really a moment of pride for us to see you here looking for joining us as a Beta tester. We really appreciate your interest to help us improving Enpass.
We release beta builds of Enpass when there are some significant changes testing of which can help us fix any issues in them before they are officially released. Beta subscribers of Enpass get them as normal update on Google Play Store and if you're not a beta subscriber, you can become one from the Enpass page on Google Play Store on the Android device. Just scroll down to the bottom and you'll see an option to Becoming a beta tester.
Alternatively you can directly access it here.
Thank you for your time and consideration!