To download the app, follow the instructions here.
Once you've downloaded the app, click on it to open the app and login. You can log in three ways- with your username and password, with a Google login, or with a passwordless email login.
To use the passwordless login click "Log In Without a Password." Enter your email address and click "Send Me a Link."
You will then see a screen confirming that an email is being sent to your email address.
In your email inbox, you will see an email with the subject line "Login To TextUs." Open the email and click on the green button that says "Login to TextUs"
Clicking that button will either take you directly to the application, or will take you to your default web browser, and you should see a popup that says "Open in "TextUs Next"?". Click on "Open."
You will then be successfully logged in to the TextUs Next mobile application!