In order to view and fill out your form offline, it is crucial that you first ensure that you have loaded the form onto your mobile device by logging into your account (while connected to the internet) beforehand.
To log in to offline mode, you will first need to enter your user email/password.
You should then see a new "work offline" option appear on the login page.
Check this box and then log in.
When you try to submit your forms while in Offline Mode it will put your completed forms into a "Sync" folder on your device.
Once you have an internet connection via WiFi or Mobile Data your device should automatically sync all forms in this folder.
If your device doesn't auto sync then you can manually sync the folder from the device. You can do this with the button in the top right corner of the "Sync" folder.