We use Testflight to distribute Beta to our testers. You need to have Testflight app installed to sign up. If you don't have it installed, you'll be asked to do so during the process.
Open this link from your iPhone or iPad device to begin:
Become Beta tester on iOS
We use Google Play Early access mechanism to distribute Beta to our testers on Android. Beta releases are not available in other stores or as APK download. You need to have an account in Google Play to become a beta tester.
Open this link from your Android device to begin:
Become Beta tester on Android