Summary
You might receive the following message while installing the Fieldwork app:
"For security, your phone is set to block installation of applications not obtained from Android Market."
By default, Google disables installing apps from unknown sources. You need to change the Android settings to allow apps from unknown sources to be installed.
Key Points
Tap Settings
Go down to Personal and tap Security
Go down to Device administration
Tap Unknown Sources, Allow installation of non-Market apps
You can now install Fieldwork.