You need to register your mobile device(s) under your user Preferences from your primary computer before logging into your community from your mobile device.
If you are using an internal community (typically for employees only): as of Jive versions 5.0.1 and higher, from your primary computer (not your mobile) click on your name in the upper right corner and go to . Enter a name for your mobile, i.e., Joey's Phone, (alternatively, you can point your mobile at the QR code on the screen if you have QR recognition software) and then click Get Activation Code. You'll then be prompted to point your mobile's built-in browser to an activation URL. From there, enter the activation code and follow the prompts to complete your mobile's registration. Then, from your mobile's built-in browser, enter the URL of your community (for example, https://widgetco.jive-mobile.com. You should see your community login page; enter your community username and password to start using your community. You can register more than one mobile device.
If you are using an external community (typically for customers, vendors, and other external audiences): from your mobile's built-in browser, enter the URL of your community (for example, https://widgetco.jive-mobile.com). You should see your community login page. Enter your community username and password and tap . Remember to uncheck if you are using a shared mobile device or just don't want your credentials stored.